Anna's advice is spot on. I would not worry or waste my chems testing CYA at this time. You are close enough. As you are keeping FC in the 20-25 range I wouldn't worry at all about CC at .5 either. If it was 2 or 3 I still wouldn't worry given your FC levels.

Love the diaper-as-skimmer sock solution! Very creative and should work at least as well as the skimmer sock, better than ladies hose, and just a little less convenient.
Carl