I don't weigh it, I go by her cues when she is full, and leftovers I freeze in ice cube trays
I like to give my LO porridge with fruits for breakfast and some sort of protein and veg puree for dinner and an afternoon snack. With breakfast I do 50g fruit puree, 30g porridge and 120ml water. It makes up to around the 8oz mark on the tommee tippee bottle and he will eat the whole thing. For dinner I mix it up but I usually do 50g steamed chicken and 150g mix of veggies like cauliflower/ broccoli/ carrots/ parsnips/ potato etc and again, that makes food enough to reach the 8oz mark in the TT bottle and he has the whole thing. I also give him a petit filous yoghurt for an afternoon snack. I make the veg one fresh daily but fruit one I make in bulk and i freeze it for a week so can melt in the boiling water and add porridge without having to wait for the water to cool etc :) I also use the water from the steamer from fruits as “juice”!
I think a rough rule of thumb is about a tablespoon of food per meal at this age but it depends on the baby. I also make more food as a lot gets spread round his mouth/goes on the high chair so that there is plenty until he decides he's had enough