I switched brands of birth control ( tri-cylen to yaz). I made the mistake of starting the new pills 4 days earlier than I normally would. I was about 1 week from expecting my period ( only 2 weeks after my last period) and I got BTB ( break through bleeding), but it was heavier than when I first got on the pill 6 months ago but not my usual flow for my period. Now I am on placebo pills and I am not getting any bleeding. So did I mess up my cycle and get my period when i had the BTB?