Temp dip before predicted ovulation date but all negative OPKs?

I’m in my first month of temping so please forgive any ignorance. I know you are supposed to have a temp dip the day before ovulation, then you can confirm ovulation with higher temps for several days after. I have watery CM but no EWCM, OPKs have been the same for days and although I only log one a day I’ve been testing a few times a day, so I know I haven’t had my surge yet. I had a temp dip this morning that I guessed would indicate ovulation is to happen tomorrow (which is what both Premom and Glow predicts) but I still have no surge? Could it just be a random dip? Or maybe my surge will be short?

Here’s my chart and the OPKs I’ve taken this week. Thanks in advance!