Pregnant or not?

Patient: So i was at my girlfriends house and we were making out. And i had and erection nd and there was a little spot in my pants of sperm..She was sitting on my lap while it happened..weve never had sex that day and we have never done it!!and im worried becuase she hasnt had her period yet!! And her stumuch hurts like out of no where..shes worried as well!! Lots of people said its impossible getting pregnant that way but im not sure..please help do u think shes pregnant or not?? Or what do you think happened?! Help please!!