Weirdest period ever. Help.

So I stopped taking BC on 11/15 I got my normal period/withdrawal bleeding on 11/19-11/22. My next AF wasn't due until 12/16 as far as glow said and I got heavy bleeding on 12/12 which got lighter yesterday and even lighter today. Took a hpt just incase this was some weord implantation bleeding and BFN. Is this normal or has this happened to any of you before? Normally I have 4 day AF and it's pretty medium so this is just weird even from before I started BC in February 2014.