Hello...I am new to this site and using opk's and needed some help. I have a 28 day cycle and started testing yesterday at 2pm (day 11) which showed a positive result on confirm (line was as dark as or a bit darker than control). Later that day I tested with First response (ran out of confirm at shops) and got a negative. Then tested again this afternoon with first response and got a positive. Has anyone else has this happen or know what the reason for it going positive/negative/positive would be?

Thank you.