I don't see this already listed so I'll mention it. Check her thyroid. Mine was on the line of being low, but not low enough for medication. Yet, we had years of problems having more children (we did already have one child). Once my thyroid was working better, we did conceive and she is a healthy happy child. I was early 40s.

We did also adopt. You have already received a lot of good advice here. I will only add that you can join adoption forums to get additional info. and find a good agency, if you decide to go that route. Sending prayers your way.