Karen Akers is tall, so tall that when she stands up, it is as if she is unfolding, length by length, in increments. Much has been written about her cheekbones, which are extreme, and her eyes, which are huge and actually are almond-shaped. Her grin, extended, is extensive. In all, it is as if someone had ordered an exceptionally striking woman, 10 percent again in size. Thus it is a relief, visiting her backstage at her Broadway dressing room where she is newly a star, when she settles her long body into a metal chair, dispatches the fans, and reveals anxieties of normal-size proportions and a relaxed and slangy style of speech.

"Babe" and "kiddo" and "truly crazy," she says, the last applied often to herself. Also--over the low roar of the humidifier--some theatrical concerns.

"There were some troubles with the sound? My number doesn't have trouble, does it? Tell me it doesn't?" she says.

The commuter-chanteuse, that's what they used to call Karen Akers when she began her famous double life; doing scales in her home on Utah Avenue when she made the kids supper; schlepping up on the Metroliner to New York to sing at the New York clubs. She kept a small apartment in New York; employed a housekeeper; and worked like crazy for a goal some of her neighbors considered crazy: to be a star, to be a name, to have both the home (in Washington) and the success thing (in New York).

Last week, after four years of the schlep, Akers, at age 36, made it. Got a shot, through the merest happenstance, at a Broadway show, her first appearance in the New York theater. The show, "Nine," opened on a Sunday night, May 9. Monday, Karen Akers was nominated for a Tony for Best Featured Actress in a Musical.

"Talk about instant gratification," the set designer says.

Karen Akers is somewhat ecstatic. Wants to give credit where credit is due, though. To her husband, Jim, a Washington lawyer whom she gets to see about once a week, these days. To her kids, who couldn't get in to see the show when it opened on Mother's Day.

"Could never do it in a million years without Jim," she says. Extended, extensive grin: "It ain't just me, babe."

And though this is the sort of thing brand new stars, giddy with pleasure and gratitude, say all the time, in the case of Karen Akers, the consummate Late Bloomer, it's at least partly accurate. Because for the longest time it just never occurred to her to be a performer. Because in the beginning, though she says she now has to be reminded of this, her husband used to have to "use all manner of persuasion" to get her to sing, and when she did, she couldn't look her audience in the face. Until it turned somehow from terror into pleasure. And from pleasure into need.

THE SHOW that is making Akers a star is a hit itself. Based on Federico Fellini's "8 1/2," it was nominated for 12 Tony Awards, right after "Dreamgirls' " 13. "Dazzling" and "elegant," the reviewers have said of the show; and of Akers' voice, "dark and dramatic"--rather an ominous, Valkyrian note for the 6-foot-tall actress who, in voluminous pink-and-white kimono, sits sprawled in her dressing room, chomping a carrot as she talks.

Akers' role, in which she plays Luisa Contini, wife of a philandering and troubled filmmaker, has been described most often as "long-suffering." But it is richer than that. With few speaking lines, Luisa communicates often with her husband in the shorthand of long-term marriage, the Look: a flash of shared amusement as he rehearses an ungainly group of amateur actresses; a bitter glance that freezes into a chilly mask as his mistress brushes by. Her songs, as well, have both been showstoppers.

"My husband makes movies," she sings in one, in defense of him. "To make them he lives a kind of dream/ In which his actions aren't always what they seem/ He may be on to some romantic theme/ Some men catch fish/ Some men tie flies/ Some earn their living making bread/ My husband, he goes a little crazy, making movies instead . . ."

Later there is a lament for "Guido Contini, Luisa Contini, number one genius and number one fan" and for Luisa, herself, an actress who once had her own career, her own dreams, and gave them up for her husband.

One wonders, then, about the actress playing Luisa--a woman, who, after all, gave up her life in New York to follow her husband to Washington, whereupon, she has said, she "cried for about 3 1/2 days."

But the story of Akers' own life, she will tell you, is the opposite of Luisa Contini's, for while she married young, at age 22, somewhat like Luisa, her interest in her work has increased since her marriage and the sacrifices in her marriage, these days, are being made predominantly by her husband and her sons, who are only 6 and 8.

And yeah, you betcha, she'll tell you backstage in her dressing room, there are sacrifices for her as well, but a different kind; she only gets home to Washington one or two days a week, she's been away much of the past four years, and those absences weigh heavily on her.

"I've had one or two days a week off since December," she says. "I've done everything I can to keep the kids' lives as normal as possible . . . they see less of me, but when I'm there I'm there for them . . . but things happen . . . like Christopher calls up all dejected because I'm not there and that makes me crazy for a couple of days . . . I get crazy easily . . . I missed a lot of things; I was in Germany when Jeremy had his first day of first grade and when I called home Jim told me how Christopher waved to him when he was leaving and said, 'Jeremy, I love you.' When I heard that, I just collapsed; your kid goes off on his first day of school by himself and you hear it for the first time on the phone . . . "

There are also, she says, strains on the marriage. Even a stranger could see why. She comes offstage after a performance so exhausted she can barely walk and, for a time, speaks of her character in the third person, as a living creature, a friend. She talks about the concentration required to create a character solely out of the imagination.

Later, she talks about the pressures: the life of the theater is a warm, sociable life, she has people around all the time, she says; her husband's work (at Sullivan & Cromwell) does not afford the same kind of closeness; her husband is a man who enjoys a social life; with her in New York five and six days, he has given a lot of that up, and it is hard. They talk on the phone, but there have been too many conversations on the phone, though there was a message, the other night, which she came home to, that just blew her mind . . . and like with the children, there is so much she is missing.

"We're moving into a new house in a week," she says. "He's doing the move; I won't get to live in that house for months. It's a huge event in the life of the family, and I'm missing out."

Then why do it? What is it that drives Karen Akers to give so much up?

She only pauses for a second before replying; in the manner of someone who has asked the question of herself and knows the answer, but is considering, briefly, whether to let someone else know.

"I don't suppose I'd be much good to Jim or the kids unless I was completing myself as a person," she says.

SOMETIMES, looking for a woman, you look to a person's mother, and if you are lucky, you learn about the mother before that mother, and then you have a clue.

Karen Akers' mother, like Akers, was a late bloomer career-wise--a mother of six who this week, Akers says proudly, receives her Divinity Degree from Union Theological; "a wonderful woman, because she never stopped growing, though I think that was difficult for my father at times." She was, as well, says Akers, an "intellectual," daughter of a former New York Times Book Review editor and his Russian wife. The wife, says Akers, with some amusement, was "a very difficult woman--my grandfather divorced and remarried and the rest of her life my grandmother referred to his wife as 'that concubine.' " Her grandmother, Akers says, was also "very old-world Russian"; a great believer in the differences between the sexes; on women being feminine, on men being men. Those attitudes, Akers feels, were passed down to her own mother--and in turn passed on to her.

"The only way I feel cheated in my childhood is . . . I'm sorry I didn't experience friendships with women . . . I think because my mother didn't experience women's lib and because of the feeling of her mother . . . you dressed for men, you didn't dress for girls; it didn't matter what girls thought, it mattered what boys thought . . ."

Also, "Mummy's an intellectual . . . someone once told me that perhaps I was living out a lot of the things she had been afraid of . . . you know the way Freud breaks it into the ego, and the super-ego, and the id? . . . that I was my mother's id . . ."

Her world, growing up, was a comfortable world. Her father, an adventurous sort who had sold aspirins in the jungles of Brazil, had been educated at Oxford, worked for most of the time as an insurance salesman. Karen, the eldest in her family, attended Catholic schools. When she was in high school, her father, convinced his family was "growing up too fast," desirous of showing his children a different way of life, left his job, packed the family up and traveled about Europe with them in a minibus. Arriving home, she went to Manhattanville College. The nuns once lectured her about her attitude there. They accused her of being arrogant and condescending. In fact, she says, they misread her: She was shy, she says, she was very inscure. She was also "unfocused." She majored in English with a minor in philosophy and math. She really had no notion of what she was gong to do. In college, someone gave her a guitar. She learned to play by watching a friend. She sang folk songs because she "liked the words" and they "seemed more honest."

She met her husband on a blind date. They married a year later. It took some urging to have her play for friends in the house--she was, after all, a person who blushed taking dictation. People told her she was good, but she "didn't believe it." She didn't believe it until she'd "been married several years." Until, you might say, other people validated her. Perhaps until a man said she was all right.

She can't pinpoint now the time she moved from terror of performing to pleasure; can't pinpoint either the time the need to perform became a pleasure, a joy. She can tell you about the time she and her husband broke up very briefly and she took perhaps her first paying job in a club, maybe because "I needed to prove something to myself." She can tell you now that performing is a "passion," that moving an audience is something she needs to do, "loves" to do.

And if this means strains on the family, well, they will try to deal with the strain. If there are no tickets for her sons on opening night, she will get them into the theater on a preview night, and tell them there are very important people in the theater and therefore it is very important for them to applaud for mummy very hard and they will and looking at them in the suits Jim bought for them, she will be proud, and looking at her, their mummy on stage, they will be proud.

If her 14th anniversary falls on the second night after the show opens and she cannot be with her husband in Washington, well, he will come to New York, to be with her here. They will do it for as long as they can do it. They will play it, as they have, day to day, by feel. And you know, she can't tell you, she says, how terrific her husband is being.

"He's an extraordinary man," she says.

"It's not just me, babe."