p.s. Columbia, Princeton, and U of Chicago are all excellent choices. If you're looking at schools like those you're going to be just fine. Breathe!

Is getting into the BEST college worth doing all that stuff?Is it even enjoyable?
Its probably different in the UK but I know someone that goes to cambridge that wasn't part of any club/organisation or sports team.

It's very different in the UK. And yes, it is worth it. Every single thing.

I know someone who got a scholarship to Yale from here and all she did extra curricular wise was Duke of Edinburgh....

To whoever neg repped me with Oxford=loser who couldn't get into Cambridge, I suggest you research how undergraduate degrees work here, you apply for a subject straight out of school and since the course I did is only offered at Oxford, UCL and Suffolk, it would be quite hard to get turned down for it at Cambridge. Although the mythical department is always known for a low success rate