I am fairly new to the OPK thing myself...this is only my second time in a year to use them. But here's what happened to me. I had several light second lines so negatives obviously. Then i tested after seeing a tiny bit of EWCM and i got NO second line at all. That was Friday morning. Yesterday I had some more EWCM and so i peed, and what do you know it was positive immediately. Then it was neg last night (the second line was lighter but not a lot) but after several girls told me they only get +s at one time of the day I tested again this AM and it was positive again...
I'm not sure what to think about them, except to say I'm having a similar experience. As long as your second line is as dark or darker then you should probably BD just in case!
I am only 2weeks post m/c so its not even one cycle after. I know my body is being weird but i'm gonna give it a shot! Good Luck!!!
Oh here's a pic of my positive if you want to see it: