Congrats and condolences.
High School was no picnic for me in the beginning. Still I dreaded leaving high school from about Grade 10 (10/12 grades in RSA). I really loved high school because the ups made the downs worth suffering. For me it was great and our class grew quite close (maybe the closest ever in my school) in the last two odd years so we were like family (it was a private school and our class was small). I had only a few bad teachers so I was on good terms with most. Anyway, I know how you feel when you say it's weird. After leaving the grad ceremony I felt "lighter" but because a piece of me was missing and because it just didn't feel real.
I'm not gonna lie and say how great life will be; the outside world is harsh and unforgiving -- one wrong move = game over! It's also so big and all of a sudden, being the top Mathematics student or being the best anthlete doesn't matter. There are a countless supply of bigger fish who are stronger, smarter or both. Also, taking responsibility for your own ass sux like a black hole.
But, on the up side, it's quite a magnificent world -- sans the people, lol -- and when you're out there, you start having loads of experiences (all kinds, hehehe) and you grow one hell ot a lot of understanding of things. I think leaving high school is like leaving Midgar on FF7 if you've never played a J-RPG before: it feels like the end but my Deity, it's just the beginning!
Advice to take/leave: Tertiary education is essential so don't slack off. You are going to get hurt -- a few times -- but you'll live and end up stronger and wiser. Focus on your career, you can follow dreams in your spare time (take it from someone who skipped uni and worked casual jobs thinking he'd just become a writer; I've struggled because of my own idiocy). Oh, and you never can have too much backup. If I could go back I would've started saving years ago and gone on to investments. I'd be living comfortably on a passive income by now if I had, or, at the very least, I'd be free of financial troubles.
Gawd, I just went OTT due to my nostalgia and regret but I think I'll leave this post. Maybe it'll be of use, even if it's to someone else.
Good Luck.
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