trying to get pregnant!

Me and my fiancé are trying to get pregnant and have been for the past 4 months without our families knowing! But for some reason it's not working. I see all these people pregnant and it's like they can do it all day long and not even mean to and since we are trying I can't for nothing! Went to the OBGYN and had my fiancée's sperm counted... everything was perfect. But I don't understand why I still can't get pregnant, it's starting to break my heart. I know we haven't been trying long. But I don't want to get discouraged! Help please!!