Welcome to healthcare magic!
I wonder that you are quite a kid and you know our website!
I agree that you may have sleep apnea
and more so if you are a bit obese for your age and if you do not have enough playing/exercises.
Most Obesity hypo-ventilation and sleep apnea people have snoring
in the night sleep so get interrupted sleep which lead to dull mentation and daytime sleepiness
You should consult your physician, if overweight
then cut down on weight and include exercises in daily routines. You are too young for such a morbid disease, please improve your life style to combat it.
I hope this advise would be helpful for you.
Still if you have any queries or doubts, please write me back,
I would be happy to solve them.
Wish you a great health!