My boyfriend got really horny while i was on my period and decided since he couldn't sleep with me, he'd just rub himself on me (no condom). He was behind me and sort of just rubbing my clit from there with his penis (he did not ejaculate but again pre-cum is a risk). The tip didn't go inside, all it did was run between my vaginal lips and my clit. Afterwards i went and wiped myself off with toilet paper just in case. I had a tampon in as well so i know he didn't go in. What are the chances that i'm pregnant?