Ok, so I'll give a little bit of background so my dilemma can hopefully make more sense. This is not me trying to brag about playing or being cocky, I simply want to provide as much info as I can so I can get the best advice. The information may help you all determine what has me utterly baffled.
I am currently a junior in high school, and just turned 17. I have been playing trumpet since 7th grade.
In high school, I started off playing second trumpet freshman year in the marching band, (mainly because we had all but 2 seniors playing first that year. I had the range, but we have a "seniority" type deal when it comes to 1st) and played a little of everything in our symphonic class.
My sophomore year, I played first in the marching band with a solo of varying range; and also played lead in the jazz band ending on a high G below double C on our version of "In the Stone" for our last performance of the year, being graduation.
This past year, I played first with 3 solos, one going up from a 3rd space B half valve slur up to 3rd line E. I also ended the 8 minute show on an 8 beat G below double C. Currently our jazz band is working on THE Maynard Ferguson arrangement of "Gonna Fly Now".
Over the years, my range has increased fairly consistently. I've been getting a little better range every single year, until now. I have hit some sort of wall and I don't know or understand what's going on. My dilemma is that, for the life of me, I can't get above an Ab below double C. I'm using plenty of air because G's are somewhat easy to me, and when my lips aren't completely blown, I can play G's an any given point in a piece. However, anything above that G is super hard, and I just can't get any higher. The written music for GFN ends on a B below double C, and I'd like to be able to play the piece by June. I really need some help and advice as to what I could do to help my range. After being able to play G's that consistently, I would think that with more range work, I should be able to hit a double C. I'm been practicing for several months to keep bumping my range up, and I'm going nowhere. What are your all's suggestions?