WHY DO I FEEL THIS WAY AFTER 'IT'

I was at my boyfriend's house last night and he started getting horny, so I played along.After 20 minutes we had sex.i've never done this before, but I think he has(he seemed like a master)I really want to do this again, but I don't want to get caught by my parents,I am sixteen after all.WHAT DO I DO IF I GET PREGNANT?!😱😱