Genetic infertilty in men?

I'm currently 8 years ttc and me and husband has been tested for infertility and every thing is fine with me

My husband sperm count is a little low and mobility also a little low but it don't seem that bad for to be still trying after so long

But I'm wondering could there be more or different tests he can be tested for other than the basic sperm analysis, he has to older brothers and they also have trouble trying to have a baby for 8 and 10 years? I'm starting to wonder is there something where missing ?