Why am I not getting pregnant?

I have a 2 year old with a different guy. Me and my fiance now are trying to have a baby. I know we both are able to have kids concidering I have one and he has 2. We've been trying for 5 months now and nothing. He's been taking methadone for quite some time now. I read that it can effect firtility but it progresses over time. Also he's got somthing called vericule or somthing (ball of viens in testis) that I read can cause infertility unless you have surgery. He's been to the doctor about it and they know he's on methadone and they know we're trying to conceive but no doctors have told us that it will effect getting pregnant. I'm at a lose here. Any help?