myshilohmy, I think you are an above average trumpet player for a highschool student. While Rowuk's words seemed harsh, don't be offended by them. You will meet much harsher critics from groups of your own peers, even though they might not be as direct and blunt about it as Rowuk. You will learn to appreciate plain, direct criticism as honest, passionate caring trumpet teaching. As for opening up your sound: Try forgetting about what your throat, neck, jaw and body are doing. Just do whatever it takes to get air out of your body and through the horn. Listen to how you want the note to sound before you play it, and you're body will do whatever is needed to supply it. A good, full sounding note starts in the head. When we first learned to talk, did our parents have to tell us where to put our tongues, how far to open up our mouths and expand our jaws? No, of course not. We learned to talk by listening and reproducing what we heard. Read what Claude Gordon has to say about this in his book, The Physical Approach to the Trumpet. I believe he talks about this in this book. Keep practicing and don't stop asking for advise and help. Play for people every chance you get.