I've seen similar threads to this on other message boards I frequent..."How do I know when I'm an artist?"..."How do I know when I'm a musician?" As it pertains to photography, my feeling is that you become a photographer the instant you push that button and record a still image of a scene. You took a photo, therefore you're a photographer. Your intentions determine whether you're a photographer, musician, or artist. Your skill level determines whether you're a GOOD photographer, musician, or artist.
If we're going to worry about whether we're a "photographer" or not, we need to be ready to face the fact that we may be a photographer...but we may be a very bad one.