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A complete set of blood tests investigating for nutrient (ferritin, iron, vitamin d, zinc etc) deficiencies and hormones would be super helpful to post in this thread if you have them.
Would you be able to get your Estradiol blood serum retested at it's highest point of your cycle (day 19-21) rather than the lowest point (day 3) so you know if low Estradiol Levels are actually contributing to your hair thinning?
I'd suggest not adding any Pharmaceutical Estradiol (like divigel) until you know exactly what type of hair loss you have and if that loss is actually due to Low Estradiol Level. Do you already have a confirmed diagnosis of Androgenetic Alopecia/FPHL from a Dermatologist? If you have confirmed diagnosis of Androgenetic Alopecia/FPHL, how was it diagnosed (scalp biopsy, DHT level, etc)?