Last month my temps looked much neater and this month they were all over the place. FF says CD16 was my OD but I had a positive OPK on CD17 am&pm and CD18 am only (darker than CD17) which went back to neg that evening. Makes me think it should be CD18???
https://www.fertilityfriend.com/home/31c32b
https://img80.imageshack.us/img80/4624/novopk.jpg
https://www.fertilityfriend.com/home/31c32b
https://img80.imageshack.us/img80/4624/novopk.jpg