If you ask average Foreign Service teens what it's like to move back to the States, you'll probably get a standard response: "Just join lots of clubs, and you'll be OK" or "It's like moving to any other post, only you already speak the language." They will tell you that all you have to do is to be outgoing, and you'll make lots of friends. Then they'll laugh and share with you the sheer joy they derived from teaching their new friends that not everyone in China lives in a hut or that Africa is more than one country.
I'd like to give you a bit of advice regarding these people: Don't listen to a word they say. Sure, they're just trying to help, but you have to remember that moving back isn't easy. I'm not saying that it's impossible--don't be afraid--but if you expect too much of the reentry process, you'll be disappointed.
Studies have shown that people who move a lot when they're young are often shy. And, while I've met quite a few outgoing people, not everybody is able to just show up at their club of choice and presto change-o suddenly be everybody's friend. There are some clubs that may typecast you for the rest of your high or middle school years. For example, although I don't mean to offend you math geniuses, you'd be surprised to find out how few people will suddenly become your friends when you join the math club. A good club for Foreign Service people who aren't afraid of raising their voices is the Model United Nations (MUN), a debate club where students pretend to be high-ranking leaders of various nations around the world. If your strengths lie in the field of visual or written arts, the yearbook committee would be good for you--at many schools it's the biggest club, but you aren't required to speak in front of large groups, and life-long friendships are often formed.
But enough about clubs. Lets talk about the United States being just like any other post--it isn't! First of all, your expectations are different when you move to the place that all you're life you�ve called home. You expect to be accepted. Secondly, most Americans have never lived overseas; so, unlike at other posts, you won't have a common past to bind you to those already there. They won't understand your life of change, and you may have trouble understanding their sedentary past. There isn't much you can do about this except to realize that you'll probably encounter it and to try as hard to overcome these differences.
One final bit of advice when you come back to the United States: be honest. People are often afraid to say where they're from, vaguely replying that they're from Pennsylvania (where their grandparents live) or that they went to private school somewhere out of State. Believe it or not, although not all Americans are as educated about foreign affairs as you are, that doesn't mean they're stupid.
Other than that, be yourself, don't expect too much, and everything should be fine.