FWIW: I thought you were a boy, as girls tend not to be so arrogant 
Admissions Officers will not discount your years of playing time – none of them. The average Yale admitted student who plays in their high school’s orchestra, my son included, have not been playing much longer than 4 years. It is the rare student, one of exceptional ability, who has played for longer.
Here’s something you should consider: When you submit an art supplement, music supplement or research project, your application is directly compared to all other student’s who have submitted a like-kind supplement. And, if your supplement is not one of the best-of-the-best that does not help your overall chances. In fact, it lessons them.
I think you are underestimating your competition – at least in terms of musical ability. There are other students who have played for ten or more years, who will have participated in summer high school programs at Juilliard, who will have played in world class venues and have won national musical competitions. Your supplement is going to go head-to-head with theirs. In all honesty, if your few years of experience is as good as their 10-12 years, then go for it. Otherwise, I would seriously reconsider submitting a musical supplement. Or at the very least, google “YouTube College Musical Supplements” and get a handle on what your competition is doing. Here I’ll get you started. This is the kid who was accepted to Juilliard, but rejected at HYP. All of these videos are 4 years old, when he was a senior in high school. Any one of these could have been submitted for a musical supplement. How do you compare?
https://www.youtube.com/watch?v=bfeoRJq4AxA
https://www.youtube.com/watch?v=mPZRE1VG0Zc
https://www.youtube.com/watch?v=mPZRE1VG0Zc
https://www.youtube.com/watch?v=oqVK3ugsaKI