Confused with opks please help

[hopeful mummy]

Ok ladies sorry to babble but I've just for the first time after trying for a year to conceive my second purchased some opks online only cheap ones as I can't afford exp ones but reviews all read good, anyway I came off my period on wed 23rd jan , done my first test on thurs then fri followed by sat both came up with 2 lines the control line clear and the second line extremely light however when I done one today had the control line and can't see another line is this normal and will they gradually become darker over the days until they match I really don't want to miss it this month

 

[baby.love]

I always find that the line varies until its a true +. I always have a second line even if its very faint, but then leading up to OV they get noticeably darker and a clear progression can be seen x

 

[hopeful mummy]

Brilliant thank you x