Re: Am I a terrible drummer?
I'm going to bombard you with questions. Is this a marching band field show? Or is this for an indoor concert band on stage? Is a drumline playing, too? Is it the full band or is a jazz band?
Playing in any of these contexts is completely different than playing in a rock band. For the most part, you stay out of the way, keep really solid time, and focus on dynamics. As a drummer in a school band, dynamics are especially important because the rest of the band subconsciously matches your volume. A few simple, tasteful, and well-executed fills are usually all it takes to liven it up.
Do you have a written part? In my experience, two-thirds of the drum set parts I've seen in concert bands are pretty much worthless. I reference them for tempo, time signatures, dynamics, and general style. Even the worst ones usually have at least a hint of where its appropriate to put those few tasteful fills. On the other third of the written parts, I follow it note-for-note just like I would if I were playing say the timpani part.
In a band with a director- especially a school band- your goal is to please the director. You have to trust that the director is coordinating everybody's individual parts to put together to please the audience. What are the director's primary and secondary instruments? Most of my directors have been drummers, so they were very hard on me, but they definitely knew what they wanted. Other directors can be relatively clueless about what they want from the drums and completely ignore them. Your director sounds like he's in the middle somewhere. He knows what he doesn't want and has a vague idea of what he wants. But he's struggling to articulate either to you. Your responsibility to the band is to help bridge that communication gap- even if at times it feels like playing pin the tail on the donkey.
Many band programs require a few one-on-one lessons with the director each semester. Does your band do this? If so, perhaps you should schedule one. One way or another, you really should try to find a chance to discuss or work one-on-one. Before you do, you should prepare some material as others have suggested. Listen to the original recordings and practice playing like that. Brainstorm and practice a few other approaches and just try them in rehearsal. There's a good chance he'll know what he wants when he hears it and let you know.
Finally, do not feel discouraged. Playing the drum set in a concert band is one of the toughest things to do as a drummer. You have to bring out the somewhat rebellious nature of rock and roll music while conforming to the composer and director's interpretation.