my wife had her last periods on 12 feb 2014 after that on 24 feb 2014 we had unprotected sex, she took ipill in 48 hours , after a week on 1 march 2014 she had spotting light bleeding for 3 days, her period was due on march 12 2014 but it did not arrive , again we took home pregnenecy test was negative , so we consulted gyneaocologist on 8 april 2014 he suggested regestrone tablet 3 times a day for 3 days she took the tablet but now till 21 april her periods did not arrive , we had beta hcg test which was negative , we did pelvis usg which was normal saying no abnormalities seen. please help what might be the problem and when will my wife be getting periods .