OMG. All of my custom brushes lost??

My Mac had system issues that were unresolvable, which made Photoshop impossible to use (beachballing - with every click and every action), so I decided to strip the computer down, reformat the drive and do a fresh install. Nothing from a Time Machine backup, which could easily have backed up the file errors that caused the issues with my system. 

Here's the problem: I thought all of my custom brushes - ages and ages of work which went into their creation - were successfully stored in the cloud, as they had been the last time I did this. Unfortunately, after a reinstall of Photoshop, they were all missing. Nearly 100 brushes, for very specific custom work ... all gone. I really don't know how I'm going to finish my current job, as I don't even know where to begin to reconstruct even a tiny portion of my brushes library. All of my custom colors are there, but not the brushes.

Am I wrong? Is it still possible that they're stored somewhere in the cloud? Why does Adobe make this so hard - why is it not automatically backed up and automatically reinstalled (or at least give you the option to reinstall) when the software itself is reinstalled? 

I'm trying not to freak out or cry ... help.