Rachmaninoff Moment Musicaux op16 no.4 Presto

[samuelaeolus]

Hello,I just turned 13 and only played 6 years and I don't currently have a piano teacher. I am obviously in a way behind others technically. But, I have finished this song and I know I have the technique for it, but I strain and apparently strike the keys incorrectly. My previous teacher went to Oberlin but she didn't help me with my technique or how I play the piano. I wanted to play this song because it represented my furry of not having a teacher (silly?). Every second I am falling farther and farther behind. No matter how long i practice if i don't practice correctly it will only hurt me.  Please tell me how to release my strain and how to properly strike a piano key. you can find the song on you-tube. Search "Moment Musicaux rachmaninoff". Thanks