Aiyoh, that's a lot lor, but honestly at 20 months with that much activity & sleep, some toddlers just have tapau-sized appetites, a few of my mum friends have kids like that too! The thing is, if he's growing well, energetic, and healthy otherwise, the quantity itself isn't necessarily a red flag, but I'd definitely check with his paediatrician just to confirm he's not grazing because he's actually not getting enough nutrition from what he's eating (sometimes they'll keep asking if meals aren't hitting the mark). One thing I noticed, so much juice & watermelon water might be filling him up without real calories, so maybe try replacing some of those with fuller foods or cow's milk instead? Since he's unwell now anyway, a quick doc visit is perfect timing to ask about his eating patterns & make sure everything's on track.