My last periods were on 17/18th Aug. after that i had sex with my boyfriend on 23-24 when my periods were just ending. After that to be double sure i had an emergency pill, after which i had very little bleeding for 2 days on 30 and 31 Aug. I thought my next periods will come 28 days after the withdrawal bleeding which should be 26/27 Sep. but today on 17th Sep I had my periods or periods like (i don't know what to call this)!! What could be the reason ? please help me here am just freaking out!!!!