CD 38 Pos Wondfo OPK but Negative CB digi advance ??

[Rainbowbbymom]

Hi ladies!

Here's my story... I have been tracking my cycles using Wondfo Opks and backing up with CB digi. I test twice a day..2pm and 8pm. By cd29 I was on 13 days of nearly pos. Wondfo opks (test line not quite as dark as control line) and 13 days of flashing smileys on CB digi advance opks (sensing estrogen surge and not LH). I stopped after CD 29 because I thought I wasn't ovulating this month. However, I've been cramping really badly and have extreme lower back pain
Yesterday at CD 37 I took a Wondfo opk at mid morning and lunch time and they were definite positives. Lunch time opk I added a cb digi advance and I got an empty circle. I am so so confused! Has this happened to anyone else? Can someone shed some light on this? Please?

 

[Wobbles]

They recommend not testing with FMU but afternoon or early evening is recommended if not both. That said you surge can go in the blink of an eye!