Trying to conceive/low sperm count

My fiancé and I have been trying to get pregnant for 2. I have two girls from my previous marriage and my OB says that I’m still very fertile with no issue. My fiancé is 38 and he doesn’t have any children. He was tested and we were told that he has a low sperm count. We spoke to an infertility doctor and he’s been doing everything the Dr told him to do but still after 2 years, not luck 😞 He exercise daily, we eat healthy, he doesn’t drink or smoke. Does anyone have any suggestions? Is there anything out there he can take that might help that anyone knows of? Currently we are looking into his new health insurance to see if they cover any infertility treatments.