I'm by no means an expert, but my BP is about the same size and has recently started eating 2 adult mice every friday. My snake doesn't have the girth yet for a small rat, but he isn't satisfied with one mouse either. He will stay out looking up and won't look for his hide until I've given him the second. See if you can get a Science teacher to let you use a triple beam balance to weigh him and the next meal.