Yeah they can be so frustrating but I still end up using them! When I first came off BCP this time, O around CD22 seemed normal for me, but then when my cycles went crazy I still kept getting the positive OPKs around CD19/20 but didn't O which was annoying, then didn't get positives when I did finally O as I'd gone through so many OPKs I ran out and only had a brand left that never even show a line never mind a positive! They have been binned now and I have a fresh batch which I was hoping to not need when I got my BFP but guess I'll be using them now! I like the Clearblue digis with the smiley face but I only have 4 left now out of my box of 20 and won't be buying more, they're so expensive!