Having trouble conceiving 3rd child

I'm almost 34 and am trying to conceive our third child. We've been trying for a year and a half, 6 months on 200 of Clomid and every negative test is getting harder to deal with. I know i want 3 children but didn't realize how much I wanted another child untill I started struggling to get pregnant. I found out my thyroid was off about 8 months ago so I've been on meds to regulate that. I had no trouble conceiving my first two amazing girls. We dont have the money to spend on tons of fertility stuff. I just don't understand why this is difficult now. My heart breaks every time I see negative.