If I sell one book per month does that make me an author?

The speaker at our local writers' group last Sunday said all authors have to be entrepreneurs, and the author/entrepreneur's life goes in three-month cycles. For weeks you'll be over the moon because your book's been released and it's selling and good reviews are coming in. Then comes that one week when you sell nothing and the world comes crashing down...

She's obviously a much more established author/entrepreneur than I am. If I sell a single book in a week I'm more than overjoyed. And if I...