Ovulation test help


Ok, so I'm going according to the app.

I got my period this month on the 6th it lasted til the 11th. I'm supposed to be ovulating on the 22nd. From the 17th and the days leading up to my ovulation day im assuming those are my fertile days right? I had sex on the 15th, I knew I wasnt supposed to be fertile til a few more days but I was curious so I took a test (first picture shown) it is now the 18th a day after my first day being fertile and this is the test I just took (second picture shown) my question is why is the second test line I took getting lighter if I'm supposed to be ovulating in a few days, isn't the line supposed to get darker?? Help please