I am so sorry for your losses

It sounds like you have had a really rough journey.
If I were you, I would go to the other clinic and see if they have any extra tests to run. And I have heard of doctors who will treat a patient with unexplained recurrent miscarriage with blood thinners on the theory that there is a clotting disorder that they aren't testing for. If you post the tests your doctor has run, we could see if there's anything obvious that's missing.