OPK Help please!

I’ve been testing for ovulation, and I’ve only gotten negative results. Usually my cycle is between 33 and 35 days. It is often irregular, though. I’ve been testing since cycle day 14 and twice a day since cycle day 16. Still no positive result and it’s cycle day 25. Is it possible that I ovulated without getting a positive test? Please help; I’m confused ! 😞 (PS this is my first cycle using ovulation tests without getting a positive result)