I agree with @Jannes Lauwers. For the purposes of this assignment (simplfying shapes) you want to make very hard edges with your shapes. Yours blend a bit too much to really read the shape design. They are soft when they should be hard (see image).

I think I would count that as finished. I might clean up some edges and re-establish some of the edges a bit more by going over them with a bit of pencil again. And look at the stem. But other then that, it looks pretty good for the project.