Drawing with Shapes

I've gotten a little busy with studying for my driver's written test but now I am back to practicing my drawing skills with this assignment of identifying positive and negative space. So I'm supposed to find a object with a simple shape and draw by marking out the negative space.
Here is my work:

In my drawing of this plastic water bottle, I started out by outlining the first layer of negative space that is the layer farthest from me which is the background behind the table. And that part was easy. Then when it comes to the bottle i think because the bottle and the edge of the drawing space is not that close I kind of just ignored the whole negative space thing (which is looking at the space around the bottle) and just drew the bottle by looking at the positive space (which is the bottle).