could I be preggo??

I went off birth control about a month and a half ago and my boyfriend and I ran out of condoms and have been having a lot of sex because we just moved into our new apartment. So he's just been pulling out, we had sex today, two days ago and the day before that and <a href="">Eve</a> told me literally right after we had sex that today is my ovulation day. He definitely came on me not in me each time, but I was wondering how much of a chance there is that I could be pregnant? I've heard it can happen from Pre cum but I'm not sure how I could tell if he had. Any advice is helpful!