Unfortunately I have also found that most doctors are not very informed and/or good at properly diagnosing patients with PCOS.
When they were testing me for PCOS, I had to have an ultrasound as well as some blood tests. The GP told me my blood results were normal, where as the specialist said there was an irregularity - they were reading the exact same blood test results so i don't know how that could be!
I'd recommend having the ultrasound done to see if they can detect any poly-cysts.
To this day I don't know if I really do have PCOS even though I display most of the symptoms - still searching for a competent doctor.
If it is not PCOS, there are several things it could be like a thyroid condition, early onset menopause, or endometrosis... just to name a few. If you suffer from depression or have had a particularly stressful year this may also be the reason you have not had your period. Changes in weight and work out intensity can also be to blame, many athletes do not get their periods months at a time.
However, I can give you the advice of changing your diet (decrease/eliminate "bad" carbs) and including exercise into your routine as it helped alleviate nearly all of my symptoms and got my period back on track. Also, the herb/vitamin Vitex also known as Agnus Castus helps many women who suffer from period irregularities and complications. And most importantly, stop stressing about it or your body may not be able to menstruate as a reaction to the stress.