Whats going on...

I been off birth control for three months now, 1st month got my period a week early and it was extremely heavy!

2nd month period was 6 days late and I had nothing but brown spotting for 2 days then one very very heavy day and then nothing, 3rd month (now) I been having cramps on n off for about a week now and for 2 days been very very light brown spotting, period isn't due till the 16th.. Is this normal? I never spot this much and always have my period 5-7 days. #TTC BTW.