Husbands low libido... PLEASE HELP

My husband and I are trying to have our first baby. Unfortunately, he has an extremely low libido. Mainly due to his antidepressants. I've tried to "spice things up". But I'm at a loss. He won't go to the doctor. We have sex at MOST once every 3 weeks. Which, that's not going to get us pregnant.

Also, I thought my having irregular periods was why we haven't conceived yet. But come to find out that I'm ovulating normally on my own due to a change in diet (low sugar and gluten free). So now, I'm not sure how to approach the issue with him. I know he'll need to have his sperm count checked.

Please help!!!