Hi, Claire,
When he first gets up at 6 or 7am, do you try to give him the bottle first thing? My lo usually wakes really hungry and will drain both sides usually, and then an hour later I give her solids. Are you giving solids at 8am and then milk at 9am? See if you give him his milk first helps, and then wait about an hour and give him his solids. If he doesn't eat a lot of solids, it's ok, as long as he is drinking his milk as that is more important.
Hope that helps,
Kathy