Period - I just started takin birth control and my doctor told me to start it that day.. I was?

Added 26 Mar 2014:

So I just started taking birth control and my doctor told me to take it the day I got it which was about ten days before my expected period. I got my period when I was supposed to but I got it during the placebo pills not during the sugar pills. My doctor told me it wot start working for about ten days. My period was longer than usual and I'm now two days into my sugar pills and haven't gotten my period and have no signs of getting it. Last months period was normal. I've been sexually active for a whole but haven't had sex in about a month and a half last time was early February. Just wondering if this is something to be worried about or just my birth control messing up my body cause it's the first month I've been taking my birth control ?