Im 18 yrs old and its almost been more than a month that i haven't had my periods. what is wrong?

Anemia and periods: If you have not had your period for a month then you won't get anemia from this. Anemia is lack of red blood cells. If you don't have your period then you aren't loosing any by your period so it won't lead to anemia. There are many reasons not to have your period. The most common is pregnancy. Pregnant women are often anemic or relatively anemic.