Clearblue opk help.

My cycle is so irregular, so I have been testing using clearblue opk. It's the one that just has a circle or a smiley face. No peek day. My last period started on the 9th and started testing opk on the 24th (the start of my fertlie window). Well I still haven't had a smiley face! Do you think that I ovulated before the "glow fertlie window" or should I just keep testing. It has detected my ovulation the two previous months, so I know it works. Last month, I tested smiley face for five days! Are these test just off or am I just over thinking this? Thanks for your help!