Are you using FF.net? Perhaps you could post the link to your chart for some reassurance.
How long are your cycles? Mine are 28/29 days long but I've Ov'd between CD16 & 20 in the past and my OPKs can go from totally negative to totally positive in just a day. In fact this cycle was the first where there was a definite gradual change.
My cycles are average 31/32 days I think. So maybe I will still Ov this month then. I am still doing opk every day early evening.
I am not sure how to link my chart but will give it a go. Thank you xx