Not ovulating

Be
We have been trying to conceive our second child for over a year now. We had no problems with our first, came back from our honeymoon knocked up lol. I was on DEPO birth control for a year after having my daughter, and haven't had any shots for 15 months. My period is still all out of sync, and I can't track my ovulation. I've been on fertility medicine this past cycle to help start ovulation. I take the ovulation tests first thing in the morning, and it's always negative, when is the perfect time to test for ovulation during the day? Is it like a pregnancy test, where its best after you've held your pee for the longest, or better at certain times a day? Thanks!!!