You have been given some great advice by the previous posters. My only concern is your other activities , baseball, football, wrestling - seasons and practice sessions melt into each other. You're probably always working on one or another sport plus, school work has to fit in somewhere. Just like too many sports can leave you too tired for homework - it can leave you too tired for chickens. Sports are fun if you are good at them and have friends around you. Caring for chickens, and cleaning coops etc. will just be you. After awhile it doesn't seem so great, especially if one bird bullies the others, a rooster overbreeds and damages the hens, predators snatch your favorite, or the flock comes down with one of the many respiratory illnesses going round. I'm not trying to dampen your enthusiasm - it's just that these are all part and parcel of being a keeper of chickens.
I was eleven when I got my first purebred puppy,(I paid for), the next year I started showing him, Then learned how to trim dogs etc. etc. This was probably much easier for me than what you want to undertake. I was very shy and horrible at sports so apart from school ,dogs where my only activity and basically my only friends. I eventually opened a grooming shop, raised many Champion dogs, wrote for breed dog magazines, and once even judged a puppy sweepstakes several states from home. But, then I wasn't giving up much - dogs were everything to me. Certainly there are people who feel the same about their chickens, or ducks, or goats. etc. My parents would not have taken over for me, if I had decided I'd rather do something else.