Irregular periods can be caused by many different types of problems. You are absolutely correct in that irregular or variable frequency periods can be caused by thyroid problems. Often women with low thyroid hormone function will find themselves with irregular periods with sometimes heavy bleeding
. In women in whom this problem is found, fixing the thyroid issue with thyroid replacement therapy usually fixes the irregular periods.
Thyroid gland problems are not the only cause of irregular periods. Often irregular periods are caused by the ovary not releasing and egg during the appropriate time of they cycle. Women with polycystic ovarian syndrome (PCOS) very often present to their doctor
with irregular periods, or the inability to get pregnant. Another cause of irregular periods is disturbances in your metabolism. For example women who are very underweight from excessive dieting or who exercise several hours per day can skip cycles for long periods of time.
I suggest that you schedule an appointment with your OBGYN. He or she can take a more detailed history of your periods and perform a thorough pelvic and physical exam. From there, your doctor will probably send off some routine blood tests. Hopefully, this will get to the bottom of why your periods are irregular. Good luck.