Ovulation

Abbey
To pinpoint my ovulation I use opk's, temping and maybe baby. I'm only new to temping so I'm not sure how much I trust my skills but yesterday my maybe baby showed heaps of ferning and today it shows absolutely nothing! My opk today aren't peak but they have two lines. Has this happened to anyone else? It's just so frustrating! 
On my first cycle of letrozole and I have pcos.
This is a photo of yesterday's maybe baby and opk's from the past two days.