C.
I am so sorry. My husband and I lost our first son at 3 days old. You are not replacing him. It can never be done, but you have to keep on living. I can't remember the movie this quote came from, but "You either get busy living or get busy diing." If you and your husband are ready for another child and your doctor says it's OK, than do what your heart feels right. No one else can tell you what's right for you. I went through some depression issues, that ws right for me, not you. You will appreciate and cherish your children all the more because af your loss.
I wish that I could tell you it gets easier, but it doesn't. I just doesn't consume my whole life.
Good Luck