What could it be

I started birth control not even month ago first time in my life. I’m 22 have two kids well I started birth control to start my period after 10 months after birth because provera didn’t work this time well I was on my third week one pill on an I had. Little light pink blood got excited my period was starting well it happen once that day the next day it was light pink once than 3rd day it was brown and that was it it said almost a week before that I was ovulating my test said so I think so what’s your girls thoughts