missed period

hey gals. I just wondering and need some reassurance. I'm about 3 days late on my period, and I think we can all agree... I'm flipping my lid. I changed the day that I start a new birth control packet from Thursday to Sunday. and this past week has been my period week,which made me PMS and blood and the whole nine yards... but not bleed. last week I went to the obgyn and had my pap and pelvic exams and everything was normal.... and I have used protection without fail for everything... I'm just nervous... any thoughts???