Why has Ovia given me this fertile window?

[Cosmomouse]

Hi, I was hoping someone who was good with charting could give me some insight into why Ovia has changed my fertile window!

Looking at temps, it seems quite apparantly that I had a dip and temp shift after the 19th, but it has now just given me another fertile period this week (which I have not only missed, but cannot figure out the logic!)

I am currently (or so I thought) 17dpo with neither af or a bfp! I usually get af 14dpo.

I know my chart is rocky (I temp vaginally) I have pcos and have been suffering hormonally this month and have spotted a few times along with having mean pms symptoms.

I guess I was just hoping to know either way pretty soon, I am hating this period of limbo!