Not bad for mouse, though key thing with avatars is you want thick lines. I mainly use 25px stroke on a 800x800 canvas and 20 or so for detailed lines. Thin lines just look bad and unnoticable
Use same forum color for background to appear like it has no background instead on png, save as jpg as it powers the file size better, and export it, in export screen you can change size to 90x90 and it will also tell you the file size and let you lower the quality down until it's undersize
Also, elbow seeming a little bitter and I like your concept for it. I might give it a shot tonight