Madcatter,My Rocky is now on two 5mg pills/daily,we started off just like you.
It takes some adjusting and testing to get it right.
I think for food,if you feed them healthy,good quality food you take care of liver,kidney functions,the best you can.
My cats are all off the dry food totally now,which I feel really good about and they love the Wellness
You can clearly feel Rockys enlarge thyroid,it's almost 1 inch long:sad: