Ovulation day

Hi

I have a 37 day cycle and have been testing my ovulation for a few months based on the app. I usually ovulate on day 22 however every other month I was not getting a smiley face. This month I tested everyday just to check and I got my smiley face on day 16. Is it possible to ovulate at different days of the cycle each alternate month? Any help or advice would be greatly appreciated. X