Ovulation after messed up period

Kaycee
I just was wondering, I just came off of birth control and this is my second period off, my first was a 26 day cycle and this one lasted for 42 before my period started today. So I'm just confused how I start calculating when I should ovulate. Should I go off of the 26 day cycle or what? I'll probably get a test kit to help. But advice would be encouraging:)