For somebody 15 years old, you are phenomenal at playing this piece. Keep it up and keep practicing it.
The piano should be used as fire wood. This piece just cannot be played on such a poor instrument. Now start practicing it on a better piano and you will play a lot better.
To me, playing such an advanced piece on a poor piano is like someone doing fancy BMX or motorbike tricks on a tricycle (maybe that is an over exaggeration but you get the drift). The instrument itself does not reflect anything to do with a person personally. Playing on poor instruments just chokes the life out of what you would be able to and want to express and this recording is a good example of this in action. The piano is more suited for Honky Tonk style music
The piano is more suited for Honky Tonk style music