I had unprotected sex a day after my safe period was over. I had my period on the 4th of march and had sex on the 11th of march and my period cycle is 28 days I immediately got postinor 2 and used them. Am I safe? And also how many days after using the pill will the bleeding start and if I don't bleed does it mean the pills didn't work or what? And is it necessary to bleed?