Hey Martin!
I'm 16 years old (quite young as well), and I know how exciting and challenging it is to virtuoso music of Liszt, Rachmaninoff, Chopin etc.
But I really need to say that the most difficult music to play (well it's my opinion), is the music by Bach and other music from this period.
You can't hide yourself here by using much pedal or by showing technical bravoura.
With this music, it really comes to musicality and consciousness of what you are playing. And the polyphonic structures make your brain work most of the time!

But again I have to admit; it's really challenging and fun to play virtuoso music!

Then I've got only one more thing to say:
EVERYBODY can play loud and fast, it's not a serious achievement.
So if you want to impress an audience, let music become alive and touch people with it.
Good luck with your recital!

Greetz, Remon