Birth control?

Hi I'm very confused, I just started taking birth control pills December 15th. Before then, my last period was November 22nd. Well I am confused as to when my next period is because on December 24 (around a month from my last period, expected time) I started spotting but very light and a brown discharge. its been heavy and light on and off and this is still going on today except now it's turning a little more reddish. I've been taking the pills all at the same time and haven't missed one at all. Is this my period? Spotting because I just started taking the pill? I will be taking pill #16 tomorrow so I haven't taken any of the last 7 of the pack yet (placebo pills with nothing in them) (which is when I thought I was supposed to get my period??) Thanks anything helps :)