What factors may cause low estrogen levels, resulting in amenhorrhea even after taking duphaston? no pcos. not pregnant.normal pelvic ultrasound.

Many things: Poor quality of ovarian follicles, resistant ovarian follicles, premature ovarian failure (all of these would be unusually rare at your age) or disorders that adversely impact hypothalamic or pituitary function such as anorexia or people with very low body fat from activities such as marathon running. For more info www.Askyourgynecologist.Org.