Confused on when i actually ovulated.

I use 3 different apps to track my cycle and ovulation. They all have the same data entered but they all say my fertile window was different days. I’m worried we missed my ovulation day. According to one of the apps it’s fine and we still have a good chance but according to this app we missed it. I thought I was 8dpo but now I’m not sure. I took a cheap Walmart test today and it’s negative I have first response pregnancy test that I plan on taking Sunday.

I might be out this cycle unfortunately ☹️Next month I will buy an ovulation kit to help narrow down when I ovulate so this doesn’t happen again.