Never bite the mouthpiece!
If you don't do it already, you need to play from your diaphragm. Fill you lungs and they use your diaphragm to push the air out, rather than using your ribs. You need a bigger (faster?) air column to play loudly, and a smaller (slower?) air column to play quieter, but both need to be well supported by your diaphragm.
If you use a soft reed, you may find eventually that you need to move up a reed strength.
Also, to play loud, you may find that you need to play quietly first - most beginners can do loud, it's quiet that's possibly harder to achieve as a beginner.