You have some interesting things that might make you stand out, including commitment to choir, environmental concerns, and, to me, the most interesting, top in the state for ballroom (and teaching). Are you considering submitting a dance video as an arts supplement, or did you stop dancing?
The essay topic sounds like the essay will be very effective. I am sorry you have suffered from problems with perception of you due to a physical difference. (Deformity is a strong word: do you use that term? Is that how you feel about it?)
Maybe your guidance counselor can explain how choir lowers your rank. Small point but my kids dealt with that as well so I understand.
Good luck!