First, don't panic!
Second, I'm in geography which is a related, but different discipline (what isn't related to geography, though?) so I'm not sure what specifically your thesis entails but I can offer you some advice from my perspective. I'm in a similar position where my thesis is primarily a review of the existing literature in a few topics to form a cohesive picture that answers my thesis question. Since my thesis does not have any kind of formal length or structure requirements, I'm writing it in the form of an academic paper. Based on this I tried to find some critical lit reviews that had been published to see how they were formatted and really loved this piece on Africa (http://www.jstor.org/stable/1343467) as he was able to review the literature and have a clear, concise topic. Using that as a model, I'm writing mine in the same manner.
This might not work for you, but maybe exploding that model out to fit a more traditional undergrad thesis would.
Good luck!