Hello, welcome to Pixelation.
Altoontoon's advice on your canvas size is sound. Trying to push all the detail you want into such a low number of pixels takes a bit of experience. The subject you've chosen has a lot of subtle tapering that is very hard to capture, but is necessary for the depiction to be successful.

A lot of your colours are very similar. You have 18 colours in your piece, many are very similar hue and value. This makes working on the piece more time consuming and difficult to manage, especially when you're starting out with pixel art. I reduced it down to 11 colours.
Line work needs to be used very sparingly when you're working with such a small sprite. Try to keep it to just outlines of the sprite's silhouette and even then only where it's really needed. Line work uses up precious pixels that you need for describing the volumes.