I have had a similiar experience. I'm on the mini pill and got AF back around two weeks after starting it. That was about the 18th of dec. Had it for a couple of days then it went away then after xmas just had some spotting. My mum suggested maybe it's not strong enough. Now i'm not sure if you class 1-2 days of light spotting as a period cause if not i'm late but have never been regular so not sure. I have decided to go off it as it has been really stuffing with my moods and I always put on weight on the pill and my body just feels all out of wack. I know that my sister bleed the whole time after she had the 3mth injection so maybe it's just a reaction some people have.
Good luck at the doctors, let us know how you go.