Hello! Ive been playing the horn for 3 years. Ever since ive always had terrible endurance and can have really good tone quality for about 30-40 minutes and can play really high and then my jaw hurts and it is extremely hard to keep playing. This has improved over the years and now i can play about 1 hoyr but still mostly people say their problems are in the lips but my lips NEVER hutt when playing but only jaw. Also i have an overbite and pretty big lips, however changing the mouth piece angle isnt something id want to do

Wth an overbite, I suspect that you may be applying too much pressure to the lips and given the angle an overbite produces, the pressure gets transcribed at an angle to the jaw. That would definitely cause pain. I had a student who had a lot of pain when she played. Very short, and her angle was strange, especially since she tried to rest the horn on her knee like everyone else. Once lifting the horn, she was able to adjust and it also forced her to face embouchure defects she relied on correcting by pivoting the horn back and forth on the knee. Finally, full lips, try a wider cup mouthpiece, and try switching to a more einsetzen style, just to see if that helps.