Lindsey, my experience with OPKs is that I always have some color to mine, though faint at the beginning of my cycle. They do start getting darker as I approach O and then turn undeniably positive. However, I know that some women get darker, lighter, darker, lighter, and then just positive. It really depends. And, much like HPTs, the more diluted my urine, the lighter the line will be.
I used to get just a few days of watery and/or EWCM prior to O, but I've had at least a week's worth for the past two cycles. So it's a good sign that you're starting to get CM, but it could still be a few days before it turns into fertile CM.
You're right around the "normal" time in your cycle to O, but if your cycles vary, then it's hard to know for sure. I will keep my fingers crossed that you get your +OPK soon. And I'll lend a pair of eyes if you need them.