hi my boyfriend and I were fooling around and he ended up cumming on my butt on my underwear and I was bent over. after he finished, we carefully took the underwear off and did not get anything in contact with my vagina. we looked at my underwear after and there were no cum spots on any part of the underwear that had contact on my vagina. I have not gotten my period yet this month, although they are usually irregular and I have been under a lot of stress and change lately. it has been about 2 to 3 weeks since this happened. is there any chance I'm pregnant?