I think she is, and I really doubt she'd gotten to second base or any other base before Leonard
. Unless you count Gerard or the horny otter. Bazinga.
If you think about Amy's character when she first came on the show, she was basically kind of frozen and robotic. It was only after interacting with Penny--presumably the only girl to ever give her a chance rather than play horrible tricks on her--that she began to come alive as something of a sexual being, probably partially due to mimicry and partially due to an increased confidence in herself. I think she had such a history of rejection, she basically just shut herself off emotionally and otherwise. Then after encountering such strong acceptance from Sheldon and friendship with Bernadette and Penny she just opened up and allowed the real AFF out to play. I don't think her enthusiasm and curiosity for experiencing all of these new things would ring quite as heartfelt, tentative and innocent at the same time if she'd had any experience in the subject before now.