Welcome! Please know that you are not alone!
It can take a while for your body to readjust... its just no one ever explains what "it will take a few months to leave your system" means.
I am in a similar boat to you. Stopped BC back in June, first period was fine, then cycle was 35 days, then normal 7 day period, then an 56 day cycle, then a 49 day cycle with AF for the first 3 weeks and spotting for the last 2 weeks, and now I am on day 10 of my current cycle and AF is still around. Almost 5 months in and mines still trying to figure it out. Just relax and it should work itself out.