Chastened perhaps, but undaunted, some 3,000 feminists descended on the Capitol yesterday to lobby against the conservative tide.

Sporting name-tags from Oregon to Virginia, women -- and a few men -- from some 80 groups applauded members of the congressional women's caucus who urged them to lobby not only for obviously feminist issues such as abortion, but also for broader social programs that the Reagan administration is threatening to cut.

"Every issue is a women's issue," said Rep. Barbara Mikulski, a Baltimore Democrat. "We have too long been identified with single issues. A budget that gets balanced by cutting food stamps is a budget balanced on the back of women. As long as military aid is sent to El Salvador and used to kill and mutilate women, foreign aid is a women's issue."

Rep. Mary Rose Oakar (D-Ohio) told the women "to fight any cutback in the Social Security system," and to lobby for five bills she has introduced "to correct inequities towards women in the system." She said "72 percent of all elderly poor are women."

Nonetheless there was a certain gloom about the future of feminist endeavors. "I'm not optimistic," said Rep. Geraldine Ferraro (D-N.Y.); "this election, women did not come out and make a difference." Rep. Bobbi Fiedler (R-Calif.), an anti-busing leader elected to Congress this year, warned that inflation is a major issue for women and that feminists should adopt "realistic" goals.