As per your request, for this week I've simply provided commentary on your code. Please read it and reflect back on your code with your partner, and see if you can't address the kinds of comments I made in your next lab.
I want to reiterate that the HtDP recipe for handling lists as presented in Chapter 9 of that text will help you a great deal in structuring your code for processing lists. Interpreters follow this kind of pattern as well, which is why we are practicing so much with structures and lists.
I feel like there was something else I was going to mention in this post, but my mind has been addled by the act of stripping wallpaper. No doubt, it will occur to me sometime a week from Saturday...