So I'm a freshman and I have been playing Trombone for a couple of years. I am lead trombone in my school's top wind ensemble. I am a pretty competent player and feel like most of my playing is pretty good. One huge weakness of mine is range. Specifically low range. I can not comfortably but consistently play the F above the treble clef and have a really strong high range. But I cannot hit the low Bb 2 lines below the bass clef staff. My playing with the trigger is soft and powerless. I know what I need to do to improve everything down to a low C but what can I do to be able to hit the Bb without changing my embouchure and just flapping my lips. All advice is much appreciated. Thank you very much, Jack.

Duplicate post. Feel free to delete once Jackr34 has another post.