Help me understand 🥺

So, with my first pregnancy I didn’t really track as much after January. I just kind of let things go as they may and I ended up conceiving

This go around for baby #2 I had my IUD pulled on the 3rd of this month (July) I’m actually wanting to track and so far I’ve done 3 ovulation tests and they’ve all said low but yet my app is telling me I’m currently in my high fertile period. I really just want to know if I should stick with logging on the app and when should I use an ovulation test?