Josh I can relate to you quite well because I actually felt the exact same way during my senior year. Yeah, it's not a good feeling. Let me tell you right now that there is no way you are going to learn game development from going to classes, turning in assignments, or reading books. Sure, those these give you a great place to start, but in my experience you are only going to learn game development if you jump in and get your feet wet by making games.
Things actually took a bit of an unexpected turn for me. I already had plans to move to an area with a lot of game companies and had even started researching the companies by playing their games and learning the same tools that they use. Then, during my last year, I was contacted by a former classmate who had joined a small startup. He wanted me to join the team as writer and designer. So I did.
Now, unfortunately, this meant that instead of jumping into a high paying job, I am sticking with my day job until something happens here, but that's not really my point.
My point is this: absolutely nothing that I ever did in any class could have prepared me for what it's like to actually be a part of a team trying to build a game. We have three artists (including our team leader), two programmers, and one designer (that's me). On one hand, it is incredibly rewarding, especially seeing that we are actually in the prototyping stage where our programmers are starting to put things into motion. On the other hand, it is a huge reality check. Suddenly vague descriptions don't work because our programmers don't think that way.
One of the absolute best things we did as a team happened this past April. We decided to take part in the Ludum Dare 23 game jam. (www.ludumdare.com
It was an eye-opening experience for all of us as we each had our assigned tasks and we tried to keep in communication with each other. Ultimately, we did not complete a game, but we DID learn a lot, and I can't stress enough...A LOT. We learned a lot about the development process, more than books or classes or assignments had ever taught us.
So do this: make a game, ideally as part of a team. A classmate of mine once said that if you get through your education without actually making any games, THAT is when you are behind.
So yes, go above and beyond on your assignments. Read everything you can get your hands on about game development. But seriously? Go make games. Make them solo. Make them with other people. Listen to everything Mr. Sloper has told you. And find a group in your college to make a game. Don't worry about 'knowing enough' to be part of a team. I'm willing to be that most of the students around you don't actually 'know enough' either, but that shouldn't stop anyone. You may have to start small, but that's okay. I am convinced that nothing will replace the experience (or at least practice) you will get from doing this. Oh, and you'll feel a lot better about yourself too. Trust me, I have been there, go out and get yourself involved in a group or two NOW, do it BEFORE you hit your senior year and you still don't have anything to show for it.