Condom came off after sex, he says his penis never touched me out of the condom but he did ejaculate

My boyfriend and I had sex last night, and when he pulled out the condom came off. Half of it was still outside my vagina, so I don't think any semen got inside me, and my boyfriend said that the condom came off at the very end and his penis didnt touch me. Is it possible that I could get pregnant? I'm in the middle of my cycle, so about the time I would be ovulating, but I'm pretty sure an egg was released at least 24 hours before we had sex. I was a virgin before this so I'm a little clueless and I might just be freaking out over nothing... Any help would be nice. %-)