Welcome to the world of thousands indie developers releasing mountains of (insert quality level X here) products in to a market place with very poor discovery tools and low-to-no curation.
Also welcome to the red herring chase of advertising your game. You will read many articles how you have to advertise, and spend as much time building your social network and advertisement network for your game to succeed as you do programming it.
I also have a game on Desura and it's not selling very well either:
http://www.desura.com/games/pirates-jewels-iiI suspect in part because Desura is not really a casual game portal like Wild Tangent or Big Fish but in any case the sales are incredibly low. I've sold considerably more copies of similar products on iOS and Andriod and Wild Tangent.
Your game also appears to be casual in nature.
It's possible your putting it in places that have the wrong audience.My gem games do a LOT better on mobile than they do on Desktop; even though I produced Pirates Jewels II specifically FOR desktop hoping to take better advantage of graphics and desktop resolution for a better game play experience it just doesn't sell well in that market place.
I do think your art is "polished" in one sense .. but it does look like it needs a pass of refinement to make it "pop" more. I hate even saying that, but in your case despite being polished it looks a little 'flat'.
Don't freak out is my strongest advice. You actually made a game. That's a huge achievement. Even if it never sold a copy you have made a gigantic that many people (even quite a few on this forum) will never achieve .. you actually finished and shipped it.
Rovio (The guys who made angry birds) made 51 games before Angry Birds. (see wikipedia article
here)
Don't have unrealistic expectations. Your first effort is often going to be mediocre in many respects. Enjoy your achievement and start understanding development is a journey. You just made the first stop, congratulations.