im not gonna be one of those annoying teenagers giving little details. so hear it goes.

my playing level.
i played the Mozart flute concerto for my audition into a youth orchestra and made 3rd chair out of 5.
im currently working on poulnec sonate for solo and ensemble and Hungarian pastoral hongroise. and im working on the Vivaldi piccolo concertos for a concerto competition.

ive only been playing for about a year though. piccolo for 2.
im in 11th grade

i started trumpet in 6th
then sax in 9th
so getting to this level on flute was quite easy.(i no longer play the trumpet and i only play the sax for jazz band)

i currently play on a yamaha 361 and i can definatly feel it holding me back.
its intonation. its odd tone colors. and its stuffyness. and yes i have gotten it adjusted my a tech.

and my youth orchestra is playing Shostakovich no. 10

Well, the easiest option would be the headjoint of course. try the better handmade ones or possibly something better from another maker.

The Yamaha mechanism itself is pretty good and to get better intonation and so on, you'd need to go up a significant level in the body.(Pearl, Sankyo, Powell, etc)

What's your budget?

im definatly getting used.

uh id say 1000-2000(stretching it)

i'd say go to a music shop (take your current flute with you) and try every thing that is with in your budget, and literaly everything better, then get the one you like the best but be sure to conduct a blind test too .