***just a warning that this might be a bit graphic**

hey sweetie,
don't know if you're still reading this thread and/or if you've sorted out what's going on. but just wanted to double check that when you said you're still a "virgin" that you meant you are not (and have never been) sexually active at all as opposed to say... letting the guy penetrate a bit, but not breaking hymen, or pulling out before he cums and/or yknow, doing whatever (i can give you all sorts of scenarios if you'd like!! ).
don't want to offend you in any way, but having worked as a counsellor for a little while i kind of get that some teens (and heck - even people my age! i'm 25) consider "virginity" to be something very specific, but sometimes you can get pregnant doing other sexual activity instead.
now, if your doc has run tests and said you're not pregnant, then great . my periods were erratic until i turned 17 and then they became like clockwork. so like others have said, it is probably just growing pains.
but if you reckon there is a possibility that you've had sexual contact with a guy, then maybe suss out the pregnancy thing further, ok?

i hope this doesn't embarrass you and anyone else in any way - and i'm genuinely sorry and mortified if it does. not my intention at all!! but yeah - just like i said - having done a bit of counselling in the past, one of the first things i learnt is that "virginity" means different things to different people, so you need to get a bit specific when you're assessing std, pregnancy etc risk.

xo deli
p.s. feel free to pm me if you want to chat a bit more in private, but no expectations because i suspect my frank talk tends to make people run in the opposite direction soemtimes .