First Fertility Consult

My husband and I have been ttc for baby #2 for around 2 years now. Our first child was conceived the first month of trying. I had no issues with that pregnancy and I had a c-section with him. We starting trying again in March 2015 and got pregnant in April, and at around 7 weeks they told us we had a failed pregnancy. At what would have been 10 weeks I had a D&E. That was early July 2015. We started trying again in the fall of 2015 and have had no luck since then. Nothing whatsoever seems to be wrong with me. I have no symptoms of anything that point to something being wrong. And my periods are always normal and my ovulation tests are always positive. So we went to the OB/GYN last month and she referred us to a fertility specialist. All she told us was that they will probably recommend an HSG and to bring my period and ovulation info from the past few months. I've never done anything like this before and was hoping someone can tell me, based off of my history, what questions we should be asking, and what info we should be providing.