My girlfriend and I were having sex and after I finished and got off of her, for a few seconds I didn't realize that the condom had fallen off of my penis and was resting on her butt. I ejaculated into the condom, most of the semen was still in it, but some semen spilled onto her anus. After wiping it off there didn't seem to be any in her vagina. I'm worried that I might have gotten her pregnant anyway. What do you think the chances of this are. What do you think I should do?