Welcome and I'm sorry to hear about your BFN Luv
I think you should be thoroughly tested for immune issues including NKC in your lining which could be done when they do the Hysteroscopy which I think you should also repeat as sometimes issues develop that weren't there previously and can be asymptomatic.
The Endometrial Biopsy will also work 2 fold to help increase the chance of implantation happening. I think you should cover all bases before doing another transfer. Best to have all your ducks in a row I reckon and you've already started that process by having PGD normal embryo's ready for transferrring