TW miscarriage - looking for similar experiences?

I had a miscarriage of my fully medicated FET last Tuesday at 7+6, with the embryo measuring 6 weeks. On the transvaginal ultrasound, my doctor and the sonographer initially thought the cause was poor embryo placement in a previously undiagnosed subseptate uterus. She has since reviewed the scans and confirmed my uterus is normal - the “septum” was actually a large amount of blood in the cavity that made it look like a septum. She isn’t sure why this happened and said she hasn’t seen it before, which is concerning given her experience and expertise.

I’m keen to hear from anyone who has had a similar experience.