What Causes Irregular And Scanty Menstruation?

I am a female, height 5 3 , weight 145 lbs. My periods are irregular, I had my last cycle in december 2016, its been 65 days I did not experience my menstrual cycle. Usually the periods are scanty , lasts 1-2 days and not too much flow. In december there was no blood at all it was just small accumulated flesh pieces that were shed , mass of dark flesh and its been 65 days now. I have taken an appointment with my gyn but here in US it takes 1 month for scheduling an appointment. I am planning to take Meprate 10 mg for 5 days. I had PCOD in 2015 but after doing strict diet and exercise my ultrasound were completely fine, I doubt that it has recurred.