OPK issues?

Hey ladies

I've been TTC for 4 cycles now, but this is my first cycle using an opk.

This past Sunday (today is Weds) I got a faint confirmation line, so I assumed that within the next day or two I would get the solid confirmation of my surge even though Glow says my ovulation day isn't till Friday. Oddly, Monday, Tuesday, and today I've gotten no result at all except for the control line. Did I miss my surge, or was it possibly a fluke? I've been testing at the same time each day.