I think the embryo quality wasn't good but RE's disagree. I went forward w/ two more transfers and got chemical and bfn. I did have a vascular consult recently who said it was my choice to try lovenox w/ a new donor cycle. HE said there are likely clotting disorders that haven't been discovered and Lovenox could help in that case.
If you think your embryos are good and donor has good history, I would do more testing. I wasted more months with 2 more FET transfers. MC's waste a tremendous amount of time as you wait for hcg to go down to 0 -- never mind the heartache.
It's possible insurance would cover testing. After my insurance co denied ART, I still went for consults and testing. They require preapproval for ivf, de and FET's but not other services.
IMO I think you should leave no stone unturned as long as finances permit.