Moving around is certainly a terrible experience for most kids, especially as much as you have moved.  There really isn't anything I can say to make this type of situation better, and you know that.  However, there is always a silver lining in situations that involve our lives.  There is always a silver lining in every bad situation, even yours.  One silver lining that comes to mind is the fact that you ARE going to be a rather well-rounded individual because of all of this.  You are going to have endless interesting stories to tell, you are likely WAY more mature than the normal young person, you are likely a bit more intelligent that the average person as well.  All of this could easily be linked to your constant moving, because it does instill a sense of independence.

Another silver lining that comes to mind is that you are almost done with this moving.  You mention that you are going for your last year of high school, so you are by all means, almost an adult.  You will soon have the opportunity to go to college, or perhaps live on your own, or perhaps both - and you will be given a lot of decision making power with those responsibilities.  You've made it this far in your life, and I certainly have endless faith that you will continue to be able to make it.  Giving up now simply is not an option, especially when the finish line is right there insight.  Push yourself just a little while longer, you're almost done with all of the moving.  :-)

- Pro