wearable × lab
Your HRV drop is tracking your iron, not your training.
Resting HRV is down 11% over 90 days. It lines up almost perfectly with the ferritin trend on your last iron panel. Heavy menstrual iron loss is the most common cause of this pattern in women your age — it throttles autonomic recovery long before hemoglobin drops. Worth a recheck and possibly a short ferrous-sulfate trial; iron bisglycinate is gentler on the gut.