HEDD Mid August/ Flo tracker

LaKaia

I use Flo to track my period and ovulation. The app keeps weirdly changing when my ovulation days are. So I don't know when I actually ovulated but, I have been having symptoms such as sore breasts, mild cramping, fatigue, headaches, etc but still get getting BFNs when I test. Does anyone know when I should actually test. Flo is now telling me I ovulated from Nov 18-Dec 1.