ditto to everything... aren't the ladies smart around here
I'll just add that I used OPKs until I saw a negative so that I knew when the LH surge was over. That way, if I O'd 12-36 hours after the last +, I wouldn't miss it. And, sometimes it's hard to tell what is truly a +OPK. Just my obsession, I guess. I ovulated earlier after my m/c so I started using OPKs around day 9 (I O on cd13).
I hope this helps. KUP!!!