AF arrives earlier each month!

Holly
Every month AF seems to arrive a few days earlier than planned! Apart from it being disappointing for TTC reasons I am getting super frustrated! 
I was on my pill for 9 years came off it in August and had a withdrawal, then my first cycle was 26 days, second Cycle was 24 and is this cycle will be 22 days! :( I am getting worried that I will never be able to pin point ovulation!