can't have a baby?

my boyfriend and i have been having sex for over 6 months. i'm on the pill so he cums in me, but i've missed pills before and i should've got pregnant. when my boyfriend and i broke up for a little another guy and i had sex and he came in me. i didn't take my pill that night either. my boyfriend and i are back together and he continues to cum in me. I dont know if i can't have kids or i just get lucky. what do you guys think?