I don't seem to be getting any better playing-wise, only worse.
I'm a sophomore going on junior year soon. I started playing in 7th grade. Next year, I will be trumpet section leader in my high school's marching band, and hopefully high brass captain. The thing is, I'm not that good. I've exceeded my current section leader but I can't progress. I have my Arbans and Clarke books that I play daily. I warm up and warm down after each concert band rehearsal and personal practice. I play over the weekends. I study music theory. I learn from what professional wind players shine on me. I love trumpet. I do everything I can but I can't: play effectively above high A, can't single tongue faster than eighth notes at 150bpm, and I can't double tongue more than 2 notes at once (and only on one pitch). I have a ton of those "I can'ts" because I physically can't get to that point. Is there something I can do to fix this rut?