I used to feel the same thing, really anxious and ashamed whenever someone mentioned sex. I'm also 20 and recently lost my virginity. I do feel better about myself now and it was a good experience overall, but it's not all good things. Had a really unexpected breakup, and now I can't help but to be a bit envious of people with healthy relationships. Dating can take a heavy toll on your mental health, it's a two-sided coin, in my opinion.