If someone missed their period for almost an entire year, received a progesterone shot that did not help, and all her blood work was clear, what could be the cause and are there any other possible treatments?

She hasn't been stressed more than usual and although she's lost some weight, she is seeing a nutritionist, and her dr. said that it has nothing to do with it

How old is "she"?

What tests have been done?

What does "she" weigh?

Is "she" on any medication?

Does "she" have any children, and if so, how old?

Is "she" breastfeeding?

She's 18 years old, still a virgin, does not have any kids,not breastfeeding,
Weighs 115 lb. not on any medication. I'm not sure but it was all sorts of blood work, from her gyno.

Anorexia? Hormonal imbalance?

Have the FSH and LH levels been checked?

shes 18 years old, still a virgin, does not have any kids,not breastfeeding,
weighs 115 lb. not on any medication. im not sure but it was all sorts of blood work, from her gyno.

When did she start menstruating, at what age? How regular were her periods before this? Has she lost weight in the last year? Is she an athlete?