TTC getting frustrated

My husband and I both in past relationships have had unplanned pregnancies that didn't end up resulting in children though. I had an abortion (please no negative comments) and his ex had a miscarriage. So if we both got pregnant perfectly fine separately years ago why is it so difficult now? Why when it is planned and we are married and stable can we not seem to make it happen? Going to be going into our 4th month of TTC soon. It's so depressing. I feel like we have been doing everything right so I just don't get it 😢.