Im pregnant due 6/7/16 my last period was sept 1st i had sex sept 9th my cycle is 28 days i cheated on my bf sept 15th whos my bd? when did i conceive

Your ovulation days: in September was likely between Sep 10 to Sep 15. If sperm is viable for 3 days average, then any intercourse between Sep 7 and Sep 18 would produce conception. In other words, it could be either man being your baby's father, depending on luck and sperm count. Sorry cannot give you a more differentiating answer. Thanks for trusting in HealthTap.