Is it normal to have 100 calories and be full?
It's possible. You'll probably be hungry later on though.
Yes, it's proportional to your weight.
Calories don't make you full. If you're well hydrated and eating low-calorie foods, it's entirely possible and normal.
yes maybe you are not that hungry the average daily calorie comsumption is 3,377 you will eat more later
if its a liquid, if you ate in the last 3 hours, or if you eat a lot. try too eat things that are filling, but dont take up a lot of space.