You have mentioned your periods have stopped when you were 15, how old are you now?? I can't answer your question directly but I can offer you this advice.

I would definitely get it checked out as there can be many things causing this. I was actually in the same boat you are in. I stopped getting my periods for quite a while when I was younger. It didn't bother me one bit but because it is not normal, I got it checked out. I was diagnosed with polycystic ovarian syndrome (pcos) which was causing the missed periods. I was given the birth control pill to make me regular. Sure enough, with the first pack, it worked. To this day, I am still taking the pill and have not missed a period since.

To be on the safe side, I would use a form of protection, if you decide to have sex, until you find out exactly if it is safe or not.

At the time it happened to me, I was a virgin, same as you, and it was not until I started the pill that I became active.

How old are you now? This happened to me when I was 13-14. Are you underweight? The reason it happened to me was because i'd lost alot of weight because of eating disorder. If you are under 100 pounds it is extremely likely that ur menstrual cycle will come to a halt.. My advice would be to go to a doctor.. And if I was you, I wouldnt risk having unprotected sex.