Negative opk yesterday, digital peak fertility today... Period ended 3 days ago. Only on cycle day 7 right now. Could opk be wrong? Temp when up. 3

14 days before. An easy way to remember ovulation is that it occurs 14 days before your next cycle. If you know how many days between periods then you can calculate an approximate ovulation date. Ovulation predictor kits can be useful but they measure the LH surge and not true ovulation. A midluteal phase Progesterone blood test is the most definitive way to confirm ovulation.