Sunflower's TTC after m/c Wish

We've been trying for a very long time to conceive. I had a m/c in 2007 and we have had no luck in conceiving. I pray for a baby everyday. Please God help me. Help me understand why? Why can't we conceive? Why is it so difficult for us? What have we done wrong? We are good people. It's just not fair. We want a baby so desperately. Please help us God. Please, please help us.