Completely down

My husband and I have been trying to conceive for months. Personally I think I am very fertile . I already have two kids and I am very regular with ovulation and cycles. The issue is that he has some health issues and we do not BD often AT ALL. Maybe one time a month. So I'm always rushed to BD around ovulation time. But truth is I think if we would BD every other day during my fertile window I would get pregnant. Any suggestions???... We are looking for some natural ways to heighten his drive. I'm so mentally drained from it all. Would invitro help at all?? Or is that way to expensive? I really need some advise