I recently went through the same thing as you. but once you start getting back and improving, you'll maybe start to like and enjoy going to practice more. An advice, talk with your gym friends alot, they help a ton, and they go through the same training and things as you. Another, be positive! Dont stress too much and stay confident. Try another month or two, and if you really hate it, then think about it. But only if you truly want to quit. You don't want to make a decision that you would regret your whole life. Think about future goals and go for them! :)
1st let me say i know how you feel, your not alone, im a gymnast too, about 6 months ago, i got a cortisone shot in my big toe because i had an inflamed joint, and im always pounding on my toe so i had to get that fixed and it still bothers me. but more recently at a meet, i did something to my back that put me on the ground and unable to move. not my back keeps poping out, and it goes numb, and it even hurts to breath at practice somedays. i go to the chiropractor and shes gonna send me to physical therapy. anyway my doctor said i need to quit. Part of my gets that, because its whats best for my health, but gymnastics is my WHOLE LIFE, and im not just leaving the sport, im leaving my coaches and my teammates who are everything to me. Take some time right now....RIGHT NOW to think, when you started gymnastics...what did u want? the trophies? medals? to be the best? to beat everyone? if this is all you wanted, then thats not what gymnastics is about. If you wanted to grow within yourself, meet new people, be coached to be the best you can be, and to love the sport and become a better athlete and a better person.....then what you wanted...is right in front of you. I know your in pain, and this pain is taking your passion for the sport away from you. i get it. i used to have so much passion and spunk in my floor routine, and now.....its not there anymore, and not only me, but my coaches can see it too that i just lost my spark. JUST BECAUSE OF PAIN! i would never have thought i would let pain decide my happiness but it is, you have to really do whats best for your health. i would take some time off, and really take this time to allow yourself to think, what would you do if this break doesnt make you better? what if it does? evaluate these things in your mind, take time to talk with your parents, coaches and doctors about what you should do. Think of this....if you didnt have an injury.....would you still have heart and passion for the sport?
Do you have to decide right now? I did gym, just at a rec level as a kid, and quit at about your age but then I went back later.
I just want to point that hitting puberty is tough as a female gymnast because your strength to weight ratio just goes to hell and sometimes that can make you feel like you just can't do anything any more and there is no point continuing but that actually isn't true. If you stick at and put in some work on conditioning outside of the gym to get your strength up, particularly in your upper body, you can get it back. In fact although girls don't make the sudden muscle gains that boys do in puberty it does still get easier for them to build muscle as they get older than it is when they are little girls. It is not easy and the way you do gymnastics is going to change but really change is an inevitable part of growing up and while it might not feel like a good thing at the time when you get older you'll see that you wouldn't really want to have the body of a child forever.
That's not to say that you should stay in gym and tough it out if you are not enjoying it. I don't think there is any point in doing gymnastics if you are not having fun with it. It is just to let you know that you do have options, and that while puberty sucks, particularly for girls, it does get better and you shouldn't let it stop you doing things you WANT to do. You can quit, see how it goes and start back later if you want to, or you can move to a rec class and do less hours, presuming you are currently in a competitive programme, or you could change to a different discipline like tumbling, trampolining or acro. It is really just a question of how you want to choose to spend your time.
I know exactly how you feel. I've been and dancer since I was two or three and I am around your age. I'm not sure I want to dance. I think you should take a break, see how it goes, and if you miss it, try again. :)