I dunno, Sean Connery's kinda furry on the chest for chocolate. Still, I'll get in line with the rest of you.
Well, Dorrie, now I know you're not the girlfriend I had when I was seventeen! The good news is you have the good sense to ask, and the wisdom to not follow all the advice given. *g* Now for my two bits..drinking alone is generally a bad idea when you're feeling down, as alcohol is a depressant. Having a dram with a friend (when it becomes legal for you) is one thing, then it can be a relaxant. Of course you know that drinking won't solve the problem, etcetc.. enough of that lecture.
Physical movement, like all that advice above to take a walk, is a very good idea. Part of this is because, if nothing else, you're changing the scenery, and you're actually doing something. Even if you're "too tired", some movement of some kind helps. Maybe it's an aid to circulation or something. Back in the 1600's, Robert Burton wrote a (now) delightfully goofy book called Anatomy of Melancholy on this very subject. This is one of the things he got right.
Also (educated guess on my part), get your school work and household chores out of the way. If they pile up on you, you'll feel overwhelmed and really depressed. This lasts well past school, Hon. I'm still trying to grow up enough to follow this advice, and I have a son your age. (Don't tell him, I'm trying to keep up the illusion that I'm a good example!) That being done, do a little something you enjoy, nothing elaborate. I have some needlework I can always pick up. I even do a bit of coloring, in one of those museum gift shop coloring books I got for just such times as this (I can't draw).
And of course, there's the music. If you're not making some, put on the radio or a CD, rather than listen in the silence to your own bummed out mood. When silence and solitude are the right thing, you'll know.