Trying to conceive please help!?

Me and my fiance have been trying to have a baby for two years now. We're intimate almost every night. I know I can get pregnant, the problem is can he have children? Is there anywhere he can go to get his sperm count checked? Or to see if he's impotent. It will be very disappointing if he is. I just don't understand why people can get pregnant in a one night stand, and why we're having so much trouble. Any advice on this situation? We really want a baby :(