yea well i dont really kno what my problem is

im a freshman this year and last year i was first chair.. this year i am 3rd.. its not that that others me but its that theres this girl in our band that has liek the exact same skills as me.. (we were tied for first chair last year)some how shes first chair this year.. in high school! i dont reallly understand why but its ok.. the stuff i am saying is leading on to my problem..i think ive lost all my self esteem.. ive gotton to a point where ppl are telling me i not be good bc im 3rd chair and ive actualyl started listening to them! i keep trying to tell myself i am good but then again think about it.. i must not be right??.. how do i raise my self esteem when it comes to my skills with my trumpet? maybe my director did this to push me to work harder but hw isnt it working? what can i do to become a better trumpet player and what can i do to help me with my high notes?..

o yea.. sumthing u might should kno.. im playing with a plastic mouth piece.. mayeb that has sumthgin to do with how i play? (reason i use the plastic one is bc im alergic to the metal ones. so its not like i could change...what can i do to sound like all the other players in my band?)