Export functions missing

Hi all,

I want to export my WordPress site per month because the server can’t handle all those years of content. The thing is, I don’t see the option to do it per month, all I see is this:
http://i.imgur.com/Jyas5nV.png

I could try to disable the Post Type plugin, but I was wondering if there is another way to export. Maybe with the export URL or something. I want to export the comments so I can import them into disqus.

Thanks for any suggestions.