This is my first time using these. I used the first one today, am on CD 14 of a normally 31 day cycle and I got a ! I'm totally shocked! FF reckoned I'd OV on around CD17 before I added today's info. Maybe I do OV earlier in my cycle which would give me a luteal phase of 16 days instead of the average 14 days, what do you all think ? Anyone else used them, what was your experience ?