Like Rachel I serve up what I think looks right but he's clear when he's had enough or I get more if he wants more. Breakfast today was 1 egg scrambled, 3 mini pancakes and half a banana he was still hungry so also some yogurt, lunch was half a bagel with cream cheese, half a kiwi and 2 cucumber sticks. Dinner spaghetti bog, the end of our garlic bread and 2 bits of tinned peach. I think he's going through a growth spurt!
Same as Rachael.. she rarely finishes what I give her, but if she does I offer something additional
I just let her tell me when shes done eating, if she finishes what i give then i offer more but if she clearly is done eating i stop & save it for the next meal