I read this charming book recently and I can confirm that both I and Heavy Metal Panda are indeed metalheads.
At 81 pages long this is shorter than most books, however, we metalheads know from listening to Napalm Death that things can be fast and wonderful. It has some great cartoons. I like the one that reads “If Highway to Hell was your wedding song” (then you might be a metalhead). My wedding songs were AC/DC’s “Up To My Neck In You”, Keel’s cover of “Because the Night” and The Ramones “Baby I love you”, so close enough!
There were a couple of things I needed to look up, since I’m a British reader. These were Yoo Hoo (a chocolate beverage) and Quinceañera (a party for fifteen-year-old girls traditional in some parts of Latin America). I nodded my head and uh-huh-ed along with this book as I’m sure other metalheads will.
You can buy this book from Amazon https://www.amazon.co.uk/gp/product/0996882642
For those who prefer a smaller bookseller it is available here http://www.volossal.com/YouMightBeAMetalhead.html