Firstly, with your CM the colour doesn't matter so much, moreso the consistency. The stretchu CM is definitely fertile EWCM, it may last for a few days before ovulation.

Secondly, with OPKs you have to have the line equal to or darker than the control line. Sadly they don't work the same way as HPTs in that a line is a line. The line will gradually get darker as you approach ovulation until it's equal to the test line, so maybe use that as an indication as well.

HTH.