Talk to Gynecologist on Gynaecology

I am a 27 year old unmarried female. I have always had a very regular monthly cycle (exact 30 days for 3 to 4 months, then a 28 day cycle for a month and then again a 30 day cycle for another 3 to 4 months). However, since the past few months, I have had a disturbed cycle. My periods get delayed from 7 to about 10 days. Last month it was a 40 day cycle too. And this month my date was also 12th feb and i still have not got my periods (date 19th feb). Also, my periods are extremely painful esp the first 3 days and the mild pain is present till day 5 in some months too. I do have a retroverted uterus. In around march, i was diagnosed with sub clinical hypothyroidism and a few months then i had a very low flow. Usually my flow is quite heavy. But ever since my flow has been not as heavy as it was. My thyroid levels are back to normal though when i last got them checked 3 months ago. My main complain is my disturbed period cycle.