OP, to be sincere with you I find myself on the same situation. Didn't really study throughout the year and may have a hard time to go to a good university. I also don't know what to do with my life, I don't have a career in mind, and after 10 years in the same school, with friends that are present on my life on a daily basis for a decade, I feel empty, alone and afraid of the future.
But being afraid won't help me, and I know it's hard to shake it off, but this feeling of sadness, it won't help you. So take a look at some careers, I mean really take a look at it and see if something interests you, at least a little bit. Also, make a study schedule and start studying, maybe you can go to a university next year
I hope this helps you, best of luck anon.
Here goes one of my favourite papes