Question to everyone I need feedback!

Okay so my period cycle is so irregular and not normal. So my boyfriend and I have been dating for two years now and in February we had sex for the first time he was my first and I was his first and it was unprotected but he pulled out before and we have had unprotected sex a few times but he always pulls out, and before we started having sex my period were somewhat regular but after I lost my virginity they have been irregular I would get it one month then it would not come for a month or two and then I would get it and I am also a swimmer so I’m in the pool two hours a day doing cardio and I’ve been a little stressed out over the summer and the last time I had my period was around July 17th and since then we have had sex 2-3 times so I’m not sure if other girls have gone through the same after they lost their virginity their period has been irregular or anything. I just need help because I’m kinda freaking out please let me know if this has happened to you!!