The most common causes are usually problems with the reproductive organs or problems with hormone levels
, though it seems your hormone levels
are fine as they already checked that. Some medications and birth control can cause you to not have a period as well. A low body weight or obesity can cause your period to cease or never even begin. Excessive exercise can cause this as well. PCOS, thyroid problems, and issues with your pituitary gland can cause Amenorrhea.