I’ve had 3 biochemical pregnancies from day 5 FETs (2 PGT tested Euploid, and one low level Mosaic). After those three, I ended up doing a mock cycle/ERA and it showed that my “window” for implantation should be 24 or more hours later. I’m about to do my second mock cycle/ERA to see if that 24 hours later window is correct. We only have one embryo left before we move to donor eggs… I want to believe that the timing of my endometrial receptivity is what made those others fail, but I can’t really get a straight answer. One Dr seemed to think it could make all the difference, and the other just blamed my loses on “old eggs” 🙄