Talk to Gynecologist on Late Periods

I had my last periods on 12 September and now it is 31 October,I have no periods till 's been 19 days from my due date that I am not having previous history is that I usually have periods 1 week after my due date but for once in a year I had my periods 15 days later of my due date so now there is 19 days gap which is not good .I usually don't eat fast food but approximately 5 to 6 times in a month. So please guide me what should as my periods are not coming.