this does sound like some teen shit

don't break your back over these issues; you should be more focused on finding out the type of person you want to be rather then feeling bad about something you did with a different person in the past

if she's bent out of shape cuz you had an experience before she was involved in your life, she's likely not a great person to have new experiences with

I guaranty you that as you get older all this stuff becomes more and more meaningless; the story of losing your virginity becomes more of a random question between partners that rivals the emotional weight of asking "coke or pepsi"

focus on making your life great and not so much on feeling bad about what happened in the past, especially with someone you thinks trying to make you feel guilty because of it