Parents don't know im not a virgin

I just feel like venting and what not, so today my mother was talking to me about how a few months ago she was on facetime with me and noticed a huge hickey on my neck, but she didnt make it a big deal at all she was just like "nothing happened after that right?" I was like "no" ... Mind ya'll i am 20 years old and living off campus in an apt with roommates. I lost my virginity at 19. I havent told my mom because i feel like she'll be upset and dissappointed and i'm not trying to deal with the akward phase and her not feeling like she can trust me. Also my father pays my rent and my mom pays my insurance everything else i pay it myself, i work. But even still i dont feel comfortable telling her, i just dont, i know whats coming next. I figure i would tell her after i graduate, if i can keep it a secret for that much longer. She constantly asks me though "Are you a virgin?" And its almost like a reflex i say "yes" it kind of sucks but i hust say to myself, its not her bizz to know anyway..but any ladies out there with me?? Lol i feel like im the only one