Ok so I have been using oak s for the past few months; and I have always of the day that my chart says I am supposed to. This month I was supposed to of on Tuesday the 31 of may. I used the opk on mon tue and wed which was the 30 31 and 1. All oak s came back pos... three days in a row... is this possible? Finally Thursday oak was neg. So when did I ov? The 31 when I was supposed to or on Thursday the 2? Please help!