My period is late!!!

So my boyfriend and I had sex on the 17th of November. The condom got stuck half way in me but my boyfriend pulled it out right away and I wiped myself right after and we stopped. He checked the condom and he said that there was no pre ejaculation in it. My period was suppose to come on December 1st but I'm 18 days late and I've been thinking that I've been stressing about this and over thanksgiving break I was busy cleaning the house for the holidays and barely got any type of sleep. Idk if there is a possibility of me getting pregnant or I'm just stressing... HELP