WP-Supercache and Still Going Slow

I’m using both WP-Supercache and have started using Cloudflare. Somehow or another, my site is still slow. It comes up anywhere between 65 and 70 in Google Page Speed tests. It says I need to optimize my images. I download the “Google optimized” image and use FTP to replace the supposedly “unoptimized” one. Then it tells me that image STILL needs to be optimized.

Also: It says I need to leverage browser caching on a number of files. I thought WP-Supercache was supposed to take care of this. Is that right? WP-Supercache says “0 cached pages, 0 expired pages” in its “Contents” tab. Does this mean it’s not working?

I saw this thread. I’m not using any of the plugins that should interfere with WP-Supercache, so what gives?

It’s really frustrating that I’m doing all this stuff to speed up my site, and none of it is working at all. Here’s the site.