Ok this is wierd for me but....?

Ok start from the begining. Me and this guy have always like each other but jave just started dating a about a yer ago. He has always "flirted" he has smacked my but and I have touched his leg but nothing bad. Nothing was on at movies so he came over to watch a DVD. Mom and dad went out to eat. Things got frisky and we ended up having sex. I guess he expected to but I was a virgin and well he had a condom but it had slid off. He came. But I'm two weeks from my period sorry if it's tmi but yea. Should I be alert that I might be pregnant?