If you cut back on the milk it should increase his food intake...I did that with my DS. If he is drinking a lot of milk he won't be hungry for food. If you think about it, if you drank a couple of milkshakes you wouldn't be too inclined to eat much either. Then offer him his favourite foods and go from there.

I found homemade crumbed chicken fingers and fish fingers to be winners because he can stab them with a fork and dip them in sauce. I put the sauce in an eggcup which he thinks is a bit special. I also make him macaroni and cheese and I put pureed spinach into the cheese sauce and that is his favourite meal. He actually thinks macaroni and cheese is supposed to be green. He doesn't eat much fruit so I let him have an inch of juice in the bottom of a cup sucked through a straw (to help protect his teeth a bit).

I can usually convince him to have a couple of spoonfuls of mixed veggies but there have been times when he hasn't ingested any veggie for about 3 days. And he likes baked beans so I give him the salt reduced version. I can't get him to eat red meat at all but he will entertain a hamburger from McDonalds so my next step is to make homemade hamburgers and sneak grated veggies into the mince mix - kind of like a rissole burger LOL.

Good luck! My DS also has a very limited repertoire and this is despite my spending hours making him little casseroles and whatnot as a baby which he loved then and totally rejects now.

And yes, I give him a vitamin. I use the Herron chewable ones - he loves them and asks for them. He knows just one a day. It makes me feel better, at least.