I have been on Yaz birth control for over a year now and have been very pleased with it. During the past year I have always been a Sunday starter. Last month I decided to start my pack on the first day of my period (Friday). However, yesterday was the last day of my placebo pills (Thursday) and I did not get my period. I have been having random aches and slight stomach aches for the past twenty four hours, but still no period. I do not think I am pregnant. Could switching my start date of the pill delay my period? I want to go back to being a Sunday starter but I am not sure If me not getting my period during the placebo pills is normal. Help!