Long time desire, very frustrated

The one thing I have always wanted to be since I was a young child, was to be a mother. I was married young and I was his third wife. He said he wanted to have another child (would have been his fifth), but he really didn't. We were married for 7 years (you can guess what happened). I went through infertility treatment after 6 years of trying to get pregnant. I quit after 6 months of humiliation because it was apparent that my ex was sabotaging the whole process. 6 months later I got pregnant. I lost it at three months. A blessings, I guess, since the marriage ended shortly after. Now, I am married to a wonderful man who truly wants to have a child with me. I am 38, almost 39 years old. We have only been trying for a few months, but I am scared and frustrated. It totally seems like everyone I know gets pregnant without trying. I've been referred to an endocrinologist and believe me, this one isn't sabotaging it, not in the least. I guess, I want to wait a few more months though. But at my age, that's against all my doctors advice. I've just started grad school and won't be done until I'm 43 years old. I don't want to wait until then and it will be hard to be a mom and a student. But, we still want to keep trying. I feel between a rock and a very hard place.