Frustrated mom of 2 boys...

I have 2 boys 11 & 5. I had healthy full term pregnancies with them and no problems at all getting pregnant. I am now married and trying for #3 bc my husband has no kids and can't get pregnant. I have had blood work done to make sure I am ovulating and he has had a sperm analysis done. Everything came back great...What do I do? We had a positive pregnancy test in February which I miscarried (chemical pregnancy) and no positive since. I am on the verge of giving up! Any advice?

***Trying to stay hopeful***