My boyfriend and I were fooling around last night, and I gave him a blowjob, he ejaculated and I swallowed it. We began French kissing and about 30 minutes later he washed his hands and then fingered me.. about another 15 minutes went by and he took his penis out and just rubbed all around my vagina, but there definitely was no penetration. I'm really worried that there was still semen on his penis when he rubbed and that I might get pregnant. What is the chance of this happening?