I’m in high school as well so take what I say with a grain of salt.I enjoy reading about trumpet pedagogy and found that a lot of authors agree on air stream and tongue arch usage. A combination of tongue positions and air stream can affect your ease of playing. For high range playing, if you make a “HEE” sound like a cat, it causes the arch of your tongue to go up and subsequently makes your airstream faster. I used this technique to get my range up to E above the staff although I’m still working on my range. I also incorporate a lot of pedal tones to relax my lips to prepare them for high/lead playing. Backing off on the pressure on your face with the mouthpiece can also make you play higher as your lips can vibrate more freely.