Hang in there girrrrrl!
Heyy!
So, I hate to sound discouraging, but if you're only 12, it may be a little while before you get your brace off 
I wore my brace starting when I was almost 11, up until I was almost 17. so over 5 years. Now, every girl is different, but typically you won't get your brace off until you are done growing. That won't happen until roughly 2 years after you get your first period. They will measure this with the growth plate in your hip, using whats called a "Risser" score. 0 means no growth, 5 means its completely grown in. now once its a 5, your scoliosis won't get worse in most cases. Now, this is just a typical case. your scoliosis might be completely different! you could not have to wear it as long! I really hope thats the case, but just remember, wear your brace! If you don't, its only hurting you in the long run. but hang in there!!!!
Hey, so I'm Rebecca, I'm 20 and I wore a Boston Brace for one year, and then a Cheneau brace for 5+ years. The Cheneau changed my life. I now am out of brace full time!!!! Its amazing. For all my scoli-girls (and guys of course) hang in there - the day you get your brace off is the best feeling ever. All the years of wearing it won't matter when that day comes. amo vobis!
"DUX FEMINA FACTI (The leader of the deed was a WOMAN!)"
-Virgel