I just got off the pain train of school so you don't have to listen to what I say.... that being said
The way you work with pencils makes me all sorts of jealous! It's really too bad I do digital stuff cuz I'd ask you for tips =D
Anyways, with regards to what your trusted adviser said about your anatomy being wrong, I believe is just in regards to proportions. Generally when doing exaggerated characters theres a few rules to follow, such as when drawings skinny characters they generally have to be tall, or when drawing pudgy characters they need to be shorter, as if all the fat was sucked out of their extremities and put into there gut! It has to do with balance of mass and its location on the character. Below I posted a quick paint over over your awesome character with the armatures listed below it. Also some kick-@ss links to some character study sites! (Unfortunately pintrest is really good for this sorta thing.) How ever you prolly should skip the anatomy part since you look really damn solid in that regards, like the porportions section!
P.S. even realistic type paintings realy on these techniques, just used more sparingly and less obvious.