Well a very fast reply:
Being 15 and playing the 2nd Ballade by Chopin is a feat on it's own. I don't remember myself EVER practicing 6-8 hours a day... Even for my diploma exams. You might think that 1-2 hours a day is not much for a 10 year old, but it's amazing, let me tell you!
That was the good thing!
The bad thing:
Although you can play very impressive stuff at this age, it doesn't mean a thing. Next year you'll be 16 and then 17 and then by the age of 20, there will be many people to play the 2nd Ballade. The age factor will dissappear.
Want to be good? Study more, go out, MAKE CONNECTIONS, meet plenty of composers (you are in the right place then), make sure you play to audiences again and again and again for money or without.
For the record, I don't really know anyone who just plays concerts and makes a living. You will need to be prepared to study, give concerts, give lessons, maybe write books, make DVDs, or whatever else it takes to pay the bills. Concerts, although pretty expensive, take a lot to be successful. I don't even remember when was the last time that I saw a pianist here in London and went "Oh! Yes! I have to see him/her". It simply doesn't happen anymore. At least in my books.
What to do right now?
When I was 15 I wanted to be a programmer. I entered the university to study physics. Now I'm a composer close to getting my PhD in composition. People change. Some don't, and I sure had music in my life, all my life. But thing is that I matured quite late in life.
Just don't close any doors. Don't say "I ONLY want to be a concert pianist, end of story. I don't need even math! I don't need history lessons" etc. Who knows what will happen? It's quite early in your life.
And be very aware: Personality plays a huge part in everyday life, whether a freelance pianist, or composer, or even a doctor, or teacher, or whatever. It means getting laid, getting married, getting hired, getting a gig, getting everything. Be friendly (like your post was and it resulted in my big post...), be wise, be patient.
[/Father Nikolas]
Sorry for the fatherly advice!

It tends to happen to me... brrrrr...