Negotiation Strategies when you have no power.

I am a High School student, I have always thought of myself as a great debater, as many people I know have confirmed.

I have a bit of a history with "anger problems" but in the last 2 years I've fixed them and gotten into the most prestigious school program in my area.  The last year there has been one isolated incident where I got in a fight, however the principle basically(though she couldn't say it aloud') agreed he deserved it and broke policy to let me off the hook.  So I started taking a prescribed medication with a rare side effect of brashness and impulsive violence.  Long story short, I am now being disallowed to go on a school trip to Germany for the summer.  I have absolutely no power, only my German teacher has power and it's very important.  All the negotiating strategies I know of are based on equals coming to a consensus when each party has something the other wants, I have nothing she wants and she has much I want.  What strategies should I incorporate?