lol no panic !!
I'm not sure how ebay uses its keywords to ensure the right sellers appear in a results page or how you can cover all odds of phrases customers may use when looking for your category of resources.
they may have some information on there to help maximise your copy text !?
You could also make a small feature on the front of your webpage alerting readers to what you have to offer ..& maybe pull out a few bits from your December planning to demonstrate the sort of things that are inside the books, have you a scanner that you can use to digitise some of the childrens work & display it on your website ?