Elizabeth,
Think of this...
1) Everything from your hips down remains straight.
2) Then try to create more space between the top of your hips and the bottom of your rib cage, by trying to pull your torso higher in the air
3) Try to move your mouthpiece about an inch higher than it is now and just don't raise your head, but try to lift your whole torso up to it.
The reason why "your feet come through your horn" is because you are probably striking the surface of the ground too hard (a lot of bands do this) with you feet. Think of pulling your weight into the air. Always lifting the body away from the ground.... Then just place enough weight in your feet to transfer your body weight to the next foot.
This also works backing up and keeps you from squatting down and sticking your rear-end out when moving backwards.
Too many people think of their body center being where it is, but if you lengthen your torso (by not compressing it) you will both look taller and also get the "feet out of the horn."
Good Luck
Eric
04-?? Phantom Regiment Visual Staff Member