5 losses in 2 years, mild focal adenomyosis, normal testing. What else should I be looking into?

Has anyone experienced something similar? I’m 28, healthy, moderately active, have normal/regular periods, and I track and confirm my ovulation every month.
I’m dealing with secondary infertility/recurrent pregnancy loss. I have a healthy child who was conceived naturally, and I had a normal pregnancy and birth with no fertility issues at the time. Since trying to have another child, I’ve had 5 pregnancy losses within the last 2 years, and almost every pregnancy ends around the exact same time, around 4 weeks 2–3 days.
I’ve had a pretty extensive workup. Clotting tests and other bloodwork have come back normal, and imaging looks good aside from mild focal adenomyosis. Nothing obvious has been found that explains why this keeps happening.
The one thing that has consistently stood out is my progesterone. My post-ovulation levels have been on the lower side and seem to have decreased over the years. Two cycles ago, I tried progesterone support, conceived naturally again, but still had another chemical pregnancy around 4 weeks.
At this point, I keep being told to continue trying, but having 5 losses happen repeatedly at almost the exact same gestational age makes me wonder if there’s something being missed.
For anyone who had recurrent very early losses/chemicals with otherwise normal testing, especially after previously having a healthy pregnancy: Did you eventually find a cause? Were there additional tests that helped, such as chronic endometritis, uterine/implantation issues, genetic testing, egg/embryo factors, or something else? Was there a treatment or change in your protocol that finally helped you carry past this point?
I’d really appreciate hearing from anyone who has been through something similar, especially those dealing with unexplained secondary infertility/recurrent loss.