Hi,
It is not unusual for menarche to be delayed in some females. You should not panic about this.
Has she noticed any other abnormal features that could point towards a hormonal or endocrine imbalance?
Is she eating well? Is her weight normal for her height? does she have any signs or symptoms of anorexia
nervosa?
It would be best to consult an OBG specialist for a complete clinical examination nad blood tests to rule out
any hormonal or endocrine causes of delayed menarche.
Let us know if you have any other doubts and post us about what hr doctor advises.
Regards.