No period??

So, in the middle of October I had "sex" for the first time. He had a condom on but I don't actually consider it to be my first time. A week or so later I had sex with my boyfriend without a condom. He didn't finish in me but the precum. I didn't get my period at all during October. Could something be wrong or something? Could it just be because of the first time that it messed up my period?