My 8 year old is built like a football player. He is about 4’6” I think but 85 Lb. he is in a gracO turbo booster But it’s like his hips are getting too wide and the seat is starting to hurt him. It seems to have happened all at once because we haven’t been riding in the car. I don’t really want him to go without so I guess I need a low back with a wider base?