How can i feel "full"? I cant stay focus in school and need help!?

Okay, im 5 ft 7 in and 144 lbs. Same weight I was EXACTLY as I was last year. Ps, i'm 14 if that helps. Recently, as in since 5th GRADE, i can never be "full". Its starting to be a real pain. My stomach, even after i've eaten still growls. And i feel gy from my stomach down to places i don't it to be. Recently i've been able to calm it with Gas X, but that helps with the gas, but not this weird "bubbling" in my stomach which gives the first signs my stomach will be growling again very soon. My parents say its from my 3 inch growth spurt in such a short time and it needs more nutrition. Or that i'm just 'bored or tired' so much in cl. Now, forcefully, i have to go to bed at 9 which doesn't help. Made things worse actually and i need to find some solution fast. I run through not as helpful as i hoped Gas X fast and where i live i have to take a thing called a TAKS test and for 3 to 4 hours i can't snack on anything like i do during the day. And when i took my first PSAT test and only because i had a bad cough and case of sniffles did i get away with my bubbly stomach. Not to mention i've gone to the doctor 2 times already going on a 3rd. If it is my growth spurt or boredom what can i do to entertain myself and my stomach. PS, whats a full breakfast i can make quick that may full my stomach up. My fiber cereal doesn't help either.