Spotting mid cycle, negative OPK's

L

So I posted a picture just for reference. Started my period July 31st. On CD 9 I had pretty intense and somewhat sharp cramping on my left side. Thought it was odd because I ovulate around CD 16-18 every month. I'm currently breastfeeding my 11 month old daughter and my cycles have been a bit longer than they used to, around 30-31 days or so, but they're very regular. Anyway, I took an ovulation test on CD 9 and it was completely negative, barely had a visible test line. Fast forward to today and I'm spotting which I never have before around ovulation or mid cycle at all. But my OPK's are still completely negative, not even close to positive and I've been testing the last 3 days. Do you still think it must be ovulation spotting? And would that happen before a positive test? Like I said, I've never spotted before so this is completely new to me.