Ovulation cramps but negative opk?

My husband and I have been ttc for 2 years now. I've used the glow app the whole time to track periods and such but before this month I never took any opks bc I thought it was pretty obvious bc I get ovulation cramps and sore breasts when I ovulate. I had an HSG (dye test) this month and an ultrasound on the same day. They said I should be ovulating on my left side this month and last night I had pretty strong left side only cramps. Glow originally estimated I'd ovulate on Saturday and last night was Sunday. Is it possible I ovulated and just didn't get a positive opk or more likely I just need to wait and will be ovulating soon? I had another negative opk this morning and still have left cramps but not as bad as last night. My cycle is usually about 35 days so I'm not "due" for AF until October 3 (today is sept 18)