Is this going to be the top, when it is sewn together? I'm a visual person, so I see that the bottom looks uneven. you may need to raise that piece up a bit. I know you probalby see this already.
Looks like you have a great portion finished. You may want to get a sheet for the backing, I have been using those. I have even used flannel sheets, they have a great feeling to them! Enjoy.