I was young too, when my disability began.
It might take some time for the doctors to get through to your parents. Maybe they are afraid that if they admit it, they'll give in to you and baby you (their issues, not yours)? IDK about caring...who ever gets "too much" caring though!
You can let this ruin the rest of your life, taking away all it's joy, or you can accept it and live life to it's fullest as you are. I hope that doesn't sound uncaring. I mean, you can't remove it, you didn't choose it...so if you spend time being angry, it's only your time that you're wasting. Yes, lots of people have disabilities and still carry on with life. I do hope that the steroids help. LOL I had so many steroids as a child (before they knew about them well) that I began singing tenor in 4th grade! (I'm a girl btw.

)...
Learn what you can about this, and keep track of what makes you feel worse, what is worth the effort (because generally there are prices to pay when we try and do something fun.) Your life isn't over, but it is changed...for now. You have no idea what cures and outcomes, changes in your body etc there might be! And if you waste time worrying or wallowing and it turns out okay, you really would have wasted that time!
Oh, and doctors can be wrong too

and it might be a more temporary thing than lifelong.