I graduated when I was 17 and went right into University.
I was like you, I didn't really know what I wanted to do, but won a good scholarship for University in a field I wasn't exactly excited about. It was a choice between Computer Science or Commerce (basically Business School Shit).
But I took it, cause at that time (The Year 2000) they stuffed it down our throats that we will have no future and no life if we did not go to University.
I wish I didn't take it. I should have taken a year too 2 years after Highschool and just found a job while I figured out if school was right for me.
I didn't flunk out or anything, in fact my grades were awesome, it just wasn't for me, I wasn't happy. So after 2 years I packed up and moved to another city on a whim and lived with my buddy and got a job with him being a Baker. lol It was actually fuckin awesome.
I knew I wasn't going to be a Baker my whole life but it was fun and a new experience for me. I also worked a part time night gig at a gas station right by my place. Ended up being a supervisor after 4 months and got experience running a team of people and all that jazz, so it ended up being a good thing. Also this was where I met my future wife.
Eventually after a few years I decided that I did wanna go back to school, I applied and was accepted and all that jazz, but another opportunity presented itself in the form of a great Job opportunity.
It was really good money for me at the time so I took it and said, School can Wait, it will always be there.
The good money job led into a better money job at a different place, which led into an even better money Job. So I still haven't gone back to school. But I currently make more money and have better benifits then 70% of my friends that did go to school.
Im 31, make enough to support 3 kids and have my wife be a stay at home Mom. I'm not rich by any means, but we manage.
The most important thing for me is I'm happy.
In the time since I left school I've:
Started my own Band as Lead Singer Guitar song writer (rocked that and live shows for 4 years)
Met a great Woman that I've been with for almost 12 years
Had 3 kids
Traveled all over hell and back playing in Video Game tournys (which I could not have done had I been in school or paying back 100,000 grand in Loans)
And a shit load of other awesome things.
The one thing I would say to you for advice is, School will always be there. Don't waste time or money even if it's not your own going to school for something you don't even care about, I mean, you just went for 12 fuckin years, do you wanna go for shit you dont' even like.
Also when you are interested in something that could be a career, do some major research into it so you know that if you go to school for 2 to 4 years for it, they will be hiring in your field when you get out. I have a ton of friends that ended up 70,000 Gs in debt for 4 years of school and don't even work in that field because there was no work.
Even my sister didn't decide till she was 25 that she wanted to be a nurse, she thought about it but waited till she was 100% sure, and now she is 1 year away from being done her schooling.
Good luck to you man. You'll figure it out. We all do.