Opk opinions please

First month using them & the first 3 days the test line was a lot darker but not as dark as the control line but today I have taken 3 through out the day..First 2 could barely see the line but this is what I got with the 3rd..Have I OVd?? Should I keep testing? According to Glow tomorrow is the start of my fertile period..I'm on CD16 going by my calculations I could be wrong though as AF is irregular normally except this month it came on time I think as I'm taking Metformin.

I appreciate all opinions