Do you have pens and paper everywhere around your home, including in the loo?
Do you find yourself writing on anything you can find, like toilet roll, napkins and even your arm?
Do you find yourself experiencing lost time because you're so immersed in you writing?
Do you wander off during conversations because you've come up with a new plot idea?
Do you use your mobile phone as a mobile word processor - as I'm doing when I'm writing this?
Then you must be a writer.
A writer is someone who is compelled to write whether they've been published or not.