Ovulation?

So I never used ovulation test before and I decided to just see if I actually do ovulate as I’ve been not actively trying but not been in anything for 2 years and I just thought maybe I don’t ovulate so on the 18th I did a test and it was positive that’s wasn’t the beginning of my fertile week my periods was from the 4-8th ton the 19th I tested again and it got lighter so could it be possible o ovulated sooner than the 18th? Tia x

This is the first test I took