Tests Rising and Falling

Jennifer

I use pregmate tests and am doing my first round of Letrazole. Last month I had positive OPKs on CD 15-16 without the medication. This month I started testing early—CD 9 and have never had a positive — it did get a little darker but never as much as the control line and now on CD 13 the line is completely gone. Could I have missed it or will it rise and fall over time?