hi, i have irregular period,my last period was july 18, 2012 then i still didn t have my period until now, i took Urine Pregnancy Test last Sept. 1, 2012, i used my 1st urine in the morning and it turned out negative, i took dydrogesterone tablet for 3 days,twice a day (sept 1-3, 2012) but i still didnt have my period until now,am i pregnant? why did the preg test last sept 1 turned out negative?