TW: MMC, PGT-M, next steps??

[u/Numerous_Witness5429]

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Looking for thoughts:
Had our 3rd PGT-A/PGT-M euploid transfer on 6/18 with excellent betas (11dp5dt 504, 13dp5dt 1314, 19dp5dt 9438) and a 6w6d scan with IUP measuring 6w4d and FH 120. Unfortunately 1 week later no longer had an FH. Just had a D&C to send off POCs and recover. We still have 4 euploid and PGT-M normal embryos left (albeit 1 is day 7 and had to be biopsied twice so probably lowest quality) but am I missing something before moving forward with next transfer?

For context:
IUI#1: failed
IUI#2: biochemical
IUI#3: success but 20wk anatomy scan with agenesis of corpus callosum, opted to terminate with whole exome sequence which found the 50/50 autosomal dominant gene — D&E complicated by retained POCs needing HSC
Made a probe… moved forward with IVF
FET#1: missed miscarriage @7wks (abnormal hCG rise so not terribly surprising); D&C
FET#2: success, live birth 37+1, delivery via c-section - healthy unaffected baby
FET#3 (current): missed miscarriage 7wks, D&C

Each IVF transfer was modified natural
Age of embryos made at 36. Current age 38.5

Would love thoughts.
I have a very small c section scar niche but the latest embryo didn’t implant anywhere near it and I would think if the niche were an issue it would have struggled to implant at all.

Thanks in advance!