I think my caching problem is fixed

A post will follow shortly (hopefully) outlining the pain I went through to get it working again.
(And yes, this does serve as a test post for the changes I just battled with)
EDIT: Turns out it isn’t yet. Will keep trying.
EDIT 2: Only problem left seems to be invalidating the main page cache on posting / editing posts. It automatically expires fine though.
EDIT 3: Debug might be helpful?

Suddenly posts from months ago

So you may have noticed that there are suddenly three new posts since March, none of which are from now.
The short answer is caching fail.
For whatever reason the caching plugin I was using didn’t expire its caches when I published posts. So although navigating directly to the post itself worked (if you followed my Twitter or Facebook links to the exact post), it wouldn’t show up on the main feed, nor presumably in RSS.
So to those of you who rely on RSS for keeping up to date, welcome back! At least you only have three posts to catch up on though!
*Will manually verify that caching is working properly when I post this post*