period help?

okay so I'm on the pill, I'm not the best with taking it though. my boyfriend and i would have sex & when he feels he's about to finish he'll put the condom on. my period is about 2 weeks late, but I've taken 3 tests and they're all negative. I've been really stressed due to school tests and family issues, and also him moving... could this be a big factor to the late period? idk what else it could be