Art Paraphrasing is the best wording. You did copy someone else's art work but not with the intent of claiming it as your own idea.

Using a pen tool is the best way to make clean lines, as Sthip suggested. (Add your program and tools so we can help). I recommend staying away from using other's artwork as directly as you did and use it as a real reference to make YOUR OWN pieces - your own ideas.

Eyes are pretty neat. Large, but neat. The anime genre uses many different styles and do use large eyes *cough* Key Company *cough*. Work on some shading and lighting on your next piece, or even on this one as an update.

Edit: and to the rest of you, what does acting obnoxious about something he's already acknowledged going to solve? Don't be dumb.