Charlie...

ANY color change indicates ketosis and you are losing weight at a very good pace for someone who doesn't have a lot to loose so you are obviously doing something right.
You really don't want to try to make those strips turn purple; purple usually just indicates dehydration so a lighter shade is actually good.
I don't honestly put a lot of stock in those test strips anyway because they can also measure digestion of dietary fat as well as other things, so they're not always the best indicator of how you're doing.
What is the best indicator? Are you losing weight and/or inches? Are your clothes looser?




Cutting your carbs well below 20 grams won't help you loose any faster and could actually sabotage your progress. If you were losing weight at 25 grams or less, go back to that level or you might even want to consider raising them another 5 grams as you progress through ongoing weight loss. You're getting close to goal, so you need to start thinking about maintainance and knowing what your level of carbs is going to be at that level.

Good luck!