Facebook description problem

There is something wrong with your theme, content is not coded correctly.
I checked your posts and the problem is also that there is only Title meta tag, but no Description meta tag. (If the post had the description meta tag the shared Facebook post would have the description despite the bad theme.)

Fix the theme or add the description to your posts via a plugin.

You can use “WordPress SEO by Yoast” plugin and go in “Bulk Description Editor” section. There you can quickly add decriptions to all current posts at once.
Also all your future posts will have the option to add the description in post editor (scroll down).