Well there are at least 7 different types of cysts, all caused by different things.
The follicle holding the egg does not rupture and release the egg, for example, an ovarian cyst can grow. But you could have caused by fluid getting trapped.
Younger women tend to suffer dermoid cysts, they cause abdominal pain.
Follicular cysts, also cause sharp pain.
If you are having trouble getting pg, it is probably a more serious type of cyst.
Early menstruation (11 years or younger) is a risk group for cysts, although the OP has a 12 year old.