First off, welcome to Soulcysters!!
Secondly, each brand has different requirements. I use
www.saveontests.com and I would pee in the morning and then maybe again but for sure on the stick around 9 or 10 am. Then I would test at night before bed. I never watched my water intake.
Once I thought I had a + OPK I tested with a digital yes/no OPK and only abstained from fluids for an hour or so and then the next time I had to pee I'd use it.
Do you know for sure if you're ovulating? Maybe you're doctor should give you a P4 test around CD 23 to see if anything is happening. You could request to be monitored though U/S as well. Are you temping?
Good luck cyster!