Has anyone used wondfo and first response opks at the same time? I used wondfos last cycle. I've been using the same batch this cycle but have been using some first response too. I'm ovulating later than I expected to this time, so I just took a wondfo which is positive. I also used first response with the same sample, and it's negative. Has anyone else happen? I'm trusting the wondfo, but it seems weird.