Increased exercise. Missed periods are common in endurance athletes.
Emotional stress.
Illness.
Travel.
Medicines such as birth control methods, which may cause lighter, less frequent, more frequent, or skipped periods or no periods at all.
Hormone problems. This may cause a change in the levels of the hormones that the body needs to support menstruation.
Well..this is not normal.
Have you consulted your GYN Specialist about this?