At one of my last seminars a hand was raised, and one of the attendees asked me if he could call himself a writer since he had never been paid to write? This is a question similar to "if a tree falls in the woods and no one hears it....." If you love to write, if the first thing you think to do when you are troubled, excited, or have a wonderful thought, is to write it down, then yes, you are most definitely a writer.
There are many individuals out there who have wonderful ideas, but struggle at the thought of how to communicate them to others. I am always amazed at the fact that some of my most needy clients are those who are the most intelligent, highly educated and street smart individuals that I have ever met. For some reason, intelligence or book knowledge does not always translate to the ability to express yourself through the written word. So for those who question what it is that makes them a writer, it is the fact that they can indeed write. And more importantly, that they want to write. The pay check is not the integral element that allows you to list your occupation as a writer? For beginning writers, in my seminars, I often suggest that it is not such a bad idea to be willing to write for free. However obscene this may be, one of the most important elements a new writer can obtain are good looking published clips. The best way to build up a portfolio worth displaying, is with your willingness to donate some writing time to attractive high gloss publications that will provide you with a byline and a digital and print clip that you can add to your portfolio.
So in essence, it is not the W2 form showing your profession as Writer with a large annual income, that allow you to introduce yourself as a writer, but it is instead that need that you possess to write. As long as you express that need by actually writing, you can definitely refer to yourself as a writer.