Do it! Don't be intimidated about writing a 300 page book, instead get a "writing" laptop and start writing snippets and scenes--you'll be amazed at what comes out of your head. I think anyone who reads a lot can write a book--you've absorbed how its done. I'd strongly recommend that you join a writing group, take a class, or attend workshops so you can listen to advice about pacing and plot, etc. Be aware you may be a seat of the pants writer, like I am, and if so don't get frustrated trying to figure out the plot ahead of time. Planning is overrated.