...Oh. So you did use a reference. I had a feeling you might have from the start, but what with the lighting, it wasn't very apparent. I suppose that took place in giving off the impression that the frog's leg, among many parts of the image were 'deformed'. It's important to know how to shade it properly, though.
Note you missed out on one of the frog's fingers hidden by shadow, and thus, the hand looks "bent". Also note, some of your lines don't exactly follow the image you traced, especially apparent on the frog's hand.
Other mistakes are rather hard to explain. So I made a bit of a guide, here, simply by shrinking what you currently have traced, albeit with a few modifications, to roughly the size you have your adoptable-thing, removing the image around it, and then cleaning it. Seems better than what you have now, so you might want to compare the two. Hope it helps.
Also, if you want to know what banding is.. Well I'll leave it to this
guide, which covers not only banding but also many other things to avoid when making pixel art. In fact, that's what the section's titled; "Things to Avoid". Section IV, part 4 is what you're looking for.
One more thing: I'm not sure if fighting back against improper anatomy in your sprites is the best thing to do. You essentially seem to be refusing critique on one aspect of your pixel art and asking for another. That's.. That's actually something that's happened many times before if I recall correctly, especially in this forum. Take it all in. Trust me, every bit of it is valuable.