You know you're a bookworm when...
You read The Complete Adventures of Sherlock Holmes Volume. 1 & 2... inside of three hours.
You have read all of your owned books at least three times over.
You get a new book, you finish it inside of an hour.
You watch a movie based on a book with your friends, and repeatedly say "Aww man, they messed that up. The book is way better-" and then get shushed loudly.
You can't find the right words to describe what you're thinking, so you quote a line from a book instead. (Much to everyone's confusion, of course.)
You start reading banking and finance books because you've ran out of other books to read. (I actually enjoy reading those, though.)
You decide to post in a topic called "You Know You are a Bookworm When...".