Hey Bballdude, thanks for the review :)
I'm about to turn 15, and when I was your age, I was still struggling with writing--I never really even tried. I just became a confident player by downloading sheet music from the internet's infinite resources (michael huang makes amazing final fantasy arrangements for piano: http://www.fantasyreborn.com)
And after a lot of growing better at piano, and certainly loving it more (since I could play stuff I really love), my teacher forced me to give writing a try. He's a big music business man, so he's pushed me so far in creativity.
I suggest you start with arranging songs you like, for me it was video game music. Try not to worry about sheet music, just become one with the piano, like you might have with your computer keyboard. It's a similar idea.
So essentially, just practice, push through those pesky frusterations (pushing or not pushing through is what separates us all in talent), and try moving outside sheet music if you haven't already.
If you ever have questions I'd love to talk! Just PM me.