Overlation

I started taken overlation test on the 6th May as glow said that was the prodicted start of my overlation. I took one on the 7th May and it was borderline negative.

So I continued to take test but after the 7th May they started going back to negative. My prodicted peak day was the 11th May but everytime I put a new test it my peak day moves it went from the 11th to now the 15th and the prodicted overlation window moved and my prodicted period has moved as well.

Do I continue taking overlation test?

Was the 7th our best chance?