PLEASE GIVE HELP AND ADVICE!! 😅

Okay this isn't gonna be short but I'm so nervous and I need some advice. Yesterday I had sex with my boyfriend, and we used a condom. He said he came and went back in for a few thrusts, but said when he pulled out after that, the condom had came about halfway off of him. The opening was still on him and I think it was on right other than being pushed up. Is it possible that it just happened as he was pulling out? How possible is it that I'm pregnant? I'm 16 and cannot get plan B, so I just really need some thoughts...