Why cant i get full!?

ok i just ate an entire bag of popcorn, 2 pop tarts, and an entire thing of ritz crackers. i ate all of that in about 10 mins. i have noticed that i havent been able to get full so i did this as an experiment and im still hungry! i thought i might have a tape worm but i researched it and i dont have any of the symptoms. this is a problem because im eating more and this is mamking me gain weight and when i dont eat i feel hungry and i get really agitated. im a 17 year old guy.