Okay, I had sex on wednesday, without using any protection. (it's a long story as to why.) I got my period the very next day, on thursday, which made me think that there's no way that one time got me pregnant. I've been reading other posts on here and heard that you can bleed even if you are pregnant. I'm really worried and don't know what to think? I know there could be a possibility, but really, how much of a chance? Thanks.