I had unprotected sex with my partner on 27th August. He ejaculated inside my vagina 3 times. We had also consumed weed and cigarette. At 1 am, 28th August I had taken an emergency contraceptive pill "unwanted 72" After which I have missed my periods. I was supposed to get my periods on 8th but till date haven't. However I had experienced a little dark blackish brown kind of flow for 2 days on 10th of September. There is little pain in my lower abdomen. Am I not on my periods because there is a chance of pregnancy or the pill has altered my cycle and therefore I will be menstruating a little late this month?