4 month late period

I am 16 years old, never had sex, never even had a boyfriend - so no I am not pregnant.
I've never been spot on regular, and for about a year I was getting my period every 1 1/2 months, this didn't worry me though. I never really kept track of my period or anything ... so I can't really tell you an exact date of the last time I had my period, but it was September/October-ish, and now it's mid January. I've been a month late before, but never more than that. I haven't really had any other symptoms besides an increase in stress/anxiety, but that is probably more due to the fact that exams are approaching and I'm busy worrying about my stupid period.
I have a doctors appt. scheduled for next week, but I just want to know if anyone else has experienced anything similar and what the outcome was. Also any advice on what could help to get my period back on track ....
Fingers crossed that there isn't anything seriously/permanently wrong.

[Dr. Kokil Mathur]

Hi!
Irregular periods or periods which do not come after a fixed number of days can be due to several causes. High level of stress, dramatic changes in your life style, high cholesterol, hormonal imbalance as seen in thyroid problems and PCOS, chain smoking, may be some of the common causes of irregular periods. Cushing’s disease and disorders of adrenal gland, tumors of the ovaries and adrenals, insulin resistance and obesity are some of the other factors. Prolonged use of oral contraceptive pills is another cause. Other important local causes of irregular periods are PCOS and fibroid uterus. PCOS causes cysts to form on the ovaries, interfering with regular ovulation. Diagnosis is by blood tests like blood insulin levels, serum testosterone and androgen levels and by ultrasound. I sincerely advice you to consult a gynecologist and get it evaluated. Take care!

The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.