Hello. Welcome to HCM.
There are causes of amenorrhoea apart from pregnancy
depending on age. At your age, common causes are functional ovarian cysts and infections. These have to be ruled out by ultrasonography
and by appropriately timed endometrial biopsy
. Apart from this you need hormonal assays and other investiagtions in blood to rule out tuberculosis
, as it is increasingly a cause of menstrual abnormalities nowadays.