never had an orgasm help!!

I'm 16 and I have a boyfriend and we have sex regurally and we do a lot of fore play before and after sex. but when we are having sex I can't orgasm and of corse he does and he tries to keep going to make me but it doesn't happen.  And we do a lot of positions as well to help but nothing. I've tried masterbation too and I still haven't had any luck. any tips or advice for me??