I am sorry about the challenges you are facing with Alex. With that in mind, I am not sure having many people post what their average (whatever that really means) toddler eats is going to ease your mind, but I am happy to tell you what mine eats. I am happy to do so because my DD, who is 25 months old, eats very little, and I am really OK with that. It is kind of my mantra for these message boards (that eating very little is not, in, and of itself, a bad thing).
So, here is what mine might eat in a typical 24 hour period:
Wake up: drinks about 6-7 ounces of milk
Breakfast: one small pancake; OR a 4 oz yogurt; OR about 1/4 cup of cereal (usually dry)
Lunch: she really just nibbles- she might eat 1/2 a PB&J or a few bites of lunch meat and cubes of cheese
Afternoon snack: a handful (my size hand) of crackers, animal crackers, or yogurt melts
Dinner: about the same amount of food as lunch, maybe a bit more
Before Bed: another 4-5 ounces of milk
So, in my opinion, that is a small amount of food. Moreover, she never really appears to be that interrested in the food. Just eats while distracted.
I am sure others will post on here and you will see the range, small eaters like mine, and bigger kids as well.