Soo scared

Hello! My boyfriend and I have sex quite often... And we rarely use a condom... He has never gotton cum on me or near me ever. He pulls out when he feels he is going to cum soon. He doesn't wait to pull out right when he's cumming, he makes sure he doesn't let it out while his penis is near my vaginal area... I'm 16, please don't judge. But this month, I didn't get my period.. And I'm a little worried. I know for a fact he didn't get his "juices" near or on me because when he pulled out, he had to touch himself more to make himself cum. He does this every time so that we don't have to worry. I just want to know if this May have something to do with the fact that I'm very active in sports, and working out a lot? I hear that has happened to people before? Or what could be going on?! Please help!!