First of all let me say that I know. I was almost the same way in highschool, and I get how frustrating it is when no one understands and they think that you couldn't have any problems because you are only 17. And it's hard as hell. But you WILL be okay.
Changing you life is HARD! and it's okay if you slip up, as long as you keep living. Don't let your weight stop you from being you.
You are not a fat person, you are just a person who happens to be fat. Don't let your weight define you. When I was in high school I let me weight define me and I was so self concious about it that I wouldn't let myself do anything. I wouldn't talk to new people (much less a guy). I told myself that I was just shy, but really I didn't think I was worth it. "Why would they want to be friends with a fat girl?" I was so wrong.
About halfway through my junior year, thanks to two really amazing friends, I realized that they were my friends because they liked me as a person, and it didn't really matter how big that person was. Because of them I slowly began to crawl out of the cave I had put myself in and realized that I
could do all of the things that I wouldn't let myself do. Over that next summer I began to make more friends who were actually worth making, and began to be more outgoing and try new things. I'm a freshman in college right now, and I don't think that my friends here would recognize the high schooler that I was before (actually they probably wouldn't notice her).
I don't know exactly what kind of person you are (shy, outgoing, ect), but I do know that once you stop letting your weight define you, it becomes much easier to lose it, because everything else isn't depending on it anymore.
Now that I've rambled on for a bit, the first suggestion I have for you is to start slow; you don't have to change your entire life in one day. The thing that I found easiest to incorporate into my life is water. Get a water bottle and start slow. For example, on the first day have a goal of drinking .5 liter of water. Then the next day try for .75 L, and so on until you reach the point where you need to be. Not only does drinking water help you loose weight, it makes you feel amazing because you will have clearer skin and more energy since you aren't deheydrated. (spelling?)
Whatever you do don't give up. Life is hard, and weight is hard, but you can make it, and we'll be here for you.
P.S. these are lyrics to a song that I play on days when everything just goes to heck...hope it helps.
It's been one of those days for a lot of days now
I need a day when the world can take care of itself
This isn't what I wanted how I thought my life would turn out
And I wonder if it's like this from here on out
Sometimes life gets you, but we go on
Sometimes life gets you, we're still going on
We're not done yet
Not going quietly into the night, not me and my friends
We're not done yet, don't take it too seriously
It's just
life will win in the end
And we walk on and on and on and we walk on and on
It's been one of those days for too many days now
I did a thing that I didn't want to do again
I fell down in the place where I always fall down and I wanna give up
And let it be what it's been
Sometimes life gets you, but we go one
Sometimes life gets you we're still going on...
We're not done yet
Not going quietly into the night, not me and my friends
We're not done yet, don't take it too seriously
It's just
life will win in the end
It's been one of those days but I don't care now
It was only a day and tomorrow's ahead
We got this far and I know that I can ride this one out
Though I want to lie down, well I won't quit yet
Sometimes life gets you, but we go one
Sometimes life gets you we're still going on...
We're not done yet
Not going quietly into the night, not me and my friends
We're not done yet, don't take it too seriously
It's just
life will win in the end