hello Doctor, im stephany 27 yrs old. i had a ceasarian operation with my first baby last to yrs back. and i keep on taking contraceptives, by then 3 mos previously i stopped. me.and my husband decided to do withdrawal method.. from dec 2015, my period is regular and sometimes it advances 4-5 days.My last period was Feb 13,2016. until now I didn't get my period. i have undergone 2 pregnancy test but it was a negative result.. Please doctor can you help me find the reasons of my delayed period?