Opk help?

Brittany • 30, Wife, Fur Mom 🐶, Baby Girl 👧🏼 2/6/19, Baby Girl 👧🏼 2/9/21

I have been taking my opk with second morning urine as I drink a lot of water throughout the day and a 3-4 hour hold is basically impossible for me. I know that in general it is better in the afternoon so if I get the opportunity I do it then. I am barely every getting any lines in the afternoon even if I had one in the morning with second morning urine. What is going on? Is this normal to have this big of fluctuation in one day. Top test is this morning on a 2hr hold and no liquids prior. Bottom is 3 hour hold with minimal liquids taken at 6pm.