they recomend about a pint of milk or 500-650ml/20oz a day but this can be in food and included cheese/yog.
if you are doing blw then just judge by him, he will eat what he wants/needs.
i vaguely remember reading somewhere that a portion size for about 8mths should be 120g of food? but basically a portion for them is what will fit in the palm of their hand, remember their tummies are still very little and for the first year most calories do come from milk, tho obviously some babies prefer solids and this become their main food.
all babies are different and the guidlines are for an average baby, so anything a bit above or below is also going to be within the normal range :)
like i said my dd has always had less milk than she 'should' and now she is on solids her appetite isnt huge, but she is!
conversely my friends ds always had LOADS of milk and has been the same with solids, he has a huge appetite, i am amazed by it! but he is dinky!
i am guessing metabolisms etc are diff in babies as they are in adults? as long as your baby is happy, gaining weight, weeing, pooing and seems content you are fine :)