Is he infertile?

Got married this July been together for almost 3yrs. We've never been pregnant. Before we were married he wanted to wait now every month he expects me to be pregnant. It's heart breaking not know what's wrong. Before we met I got checked. To make sure i was fine. I've carried twins so i know it's possible for me. But.. I think he's not fertile. How do I break this to him? We really want our own.