I'm glad your studies are progressing so well. I had the finger skills for Appassionata at your age, but not the emotional life to understand it or like it. I'm much more interested in it after a few loves lost. I suggest you listen to the concertos and pick out the one you have a passion for. You are going to live with the piece for a year or more, find the one that you like the most, as well as matching your current skill set. I recently heard the Liszt Totendanz and liked it enough to write it down on my list of things to buy on LP, but that is me, not you.Another thing to consider is what skill the orchestra has to have to play the score. If you pick something that an advanced high school district orchestra could play, that increases your chance of actually getting to play live.
If this is your first concerto, keep in mind there will be challenges other than the piano part. This is not solo music, you will need to be working with other musicians. If you haven't done much ensemble work, perhaps a less technically difficult concerto would enable you to concentrate on building your ensemble skills without fretting too much about your own part. indianajo makes a good point. If you pick a piece playable by a high-school or community orchestra, you will have much more performance opportunities. Also keep in mind concertos like both the Chopin selections, are also available for a string quartet arrangement.