It depends on your diet. If you eat really bad and alot at one time you get used to that. When you eat only a little at one time like smaller amount than usual you still feel hungry. Try cutting a little more and your body will get used to it.
You are probably witnessing a growth spurt. I used to get them all the time. Your body needs the energy so you can grow thus you getting hungry within 10 min of eating. I would suggest having a snack about 20-30 min before each meal if possible so you don't feel as hungry after a meal.
You might not even actually be hungry. A lot of people eat when they get bored. I know I do. I say I'm hungry and look for things to snack on but I'm actually not even hungry at all. Try eating more at supper time and have a snack afterwards if you really get hungry. Try to eat big meals rather than small snacks. Small snacks won't will you up, which is why people keep snacking.