Screw you AF!

Abi
I came off of birth control months ago. I had two regular periods both on the same cycle day.
I thought I'd cracked it. Then this month, I was 20 days late & still getting bfn.
Then today BAM AF! 😔 on cd 57!
So confused as to what the hells going on with my body 😔
Anyone else had this problem? What could it be? Should I be worried?