I thought that orijen cat and kitten dry is more like 20% carb. Where did you get 13% from?
As you are doing TR it is best to find a HC wet food that he will eat, then you can squeeze out the gravy (that's were most of the carbs are) when you need it. It was ok to use it today, but with TR it's important that there is no dry food in the picture, it is one of the prerequisites.
In the absence of wet HC food you can add honey or syrup to his regular food, to increase the carbs load.
Based on today's numbers I wouldn't describe him as being overly carb sensitive. I would have expected to see a hike in numbers if he were very carb sensitive.
But enough of that.
Lovely green run of numbers



