Here I am, after checking your portfolio in more detail. There was less pieces than I expected. Anyway, most of them are pixel-art, so it's enough to get an idea.
I think the better ones are here: http://guedzilla.deviantart.com/art/Pixelart-Objects-Furniture-433397157
Dithering is not bad at all, design is ok.
The 2 backgrounds are a bit too rough instead. Not that it's an easy task to paint backgrounds! In fact, it's one of the most difficult things to do when it comes to pixel-art. Small pieces are easier to achieve, but still require some competence.
And your pen sketch shows you have some talent in the visual field.
For this reason, I think it's worth giving you a chance to show what you're capable of. I'm still overwhelmed by things to do, so don't expect this in a couple of days, but I'm going to send you a list of small tasks to see if you can contribute something to the game in a fit style. I'll get back to you using the email you registered with; if it's not an address you use often, please PM me with the preferred one.
In the meantime you might play the game again, and study the graphic style.
Last but not least: thanks a lot for your offer and for the enthusiasm that transpires from your words.