If you disabled your caching plugin then I should not see the following at the bottom of the feed, yet I still do:
<!-- Quick Cache is NOT caching this page, because $_SERVER['REQUEST_URI'] indicates this is a /feed; and the configuration of this site says not to cache XML-based feeds. -->
The URL I used is a "hack" sort of speak, all I did was pass in additional parameters to the URL in the form of a GET query string, what many web sites use for search URLs. This almost always bypasses any caching and goes straight to the site. Use for testing is ok, but I would not use that random URL I created for production use as it will not be cached, which caching is something you will want if it is needed down the road.
Make sure you keep the caching plugin disabled. Also double check it did not modify your .htaccess file, if it did it may still be working even if it's disabled.