Never getting positives!

Hey all! I’m curious if any of you have confirmed ovulation but never get positive opk? I’ve been testing 2x a day, I’ve had all the signs with my cervix and CM, and even majorly severe cramps on CD 15 (and I mean severe) and even took 3 tests that day, but none of them are quite there, they look a bit darker in this photo than in real life.

Do you HAVE to get a positive? I’m wondering if I should assume that I didn’t ovulate despite other signs (my bbt is coming in the mail so won’t do me any good this cycle).