Call Me a Writer?

What do you do?
I'm a writer.
To me, the word writer is so loaded. A writer can mean a journalist, a blogger, a magazine writer, or yes, even an author. What am I though? In her book The Year of Secret Assignments Jaclyn Moriarty slips in a crack that, though I don't remember the exact quote, is something to the extent of "a writer is anyone who has written words". (Once again, not quoted precisely) So then, what am I? I write, for sure I do. I write papers for school, I practice my cursive in classes when I'm bored, I write hundreds of emails a day. Would that make me a writer? Or do I need to write something else to call myself a writer? I write poetry (infrequently), short stories (learning how) and of course, I'm working on a novel (which sounds pretentious, overwhelming, and scary all at once). Do writing these more typical pieces make me a writer? At this point, of course I'd just like to say yes, but calling myself a writer sometimes seems scary.
As I've done before, I'm going to turn to the Dictionary app on my computer. Unsurprisingly, there are eight definitions. Here they are for your viewing pleasure:

writer |ˈrītər|
noun
a person who has written a particular text : the writer of the letter.
• a person who writes books, stories, or articles as a job or regular occupation : the distinguished travel writer Freya Stark.
• [with adj. ] a person who writes in a specified way : Dickens was a prolific writer.
• a composer of musical works : a writer of military music.
• Computing a device that writes data to a storage medium.
• Stock Market a broker who makes an option available for purchase or sells options.
• [with adj. ] a person who has a specified kind of handwriting : neat writers.
• Brit., historical a scribe.
• Brit., archaic a clerk, esp. in the navy or other government offices.

See how hard it is to define writer? I guess that the first definition formalizes what Moriarty wrote and the second definition is what I aspire to. But there are some other more random definitions which I didn't even think about or consider such as a composer (totally relevant), a computer device (I'm technology challenged), and a stock broker (something I never want to be involved with). 
I guess what I'm asking is, is it arrogant of me to call myself a writer? I tell people all the time that "I write", but somehow it seems less significant than calling myself a writer. Write is something I do as a hobby or for fun. Writer is a title and in my mind it is one short step from writer to author which is an occupation or a career (at least to me). And that is scary. Scary I guess because it's everything I've ever wanted and everything I've never wanted to say (or type) aloud. All I want from life is to sit at home every day and write/edit. I want to be able to walk into a book store, go to the young adult section, pull out a book and see my name on the cover. I've wanted this since I was six-years-old and told everyone that I wanted to be an author/illustrator (even when I didn't know quite what that entailed or meant). So calling myself a writer? Somehow it's a step towards my dream, towards what I've been working for.

Am I a writer? I think so. I'm a blogger both with this blog, and the newly updated Echoes blog (check it out http://barnardechoes.wordpress.com/). I write so many papers a semester for all my classes. And I discovered the other day that my writing process for writing a paper and a fictional piece are surprisingly similar. I like that the analytical side of my literature studies and the creative one are starting to bleed together, especially because the Barnard English department stresses that in order to be a good writer you have to be a good reader. And I'm still writing fiction. I'm editing Guardians and writing new pieces for my class. I'm about to start a new five-page sample to apply to new creative writing classes next semester. So yes, I am a writer. 

I just got chills a bit as I finished that last line. I don't think I've ever publicly referred myself as a writer before. But I think that as I've worked through my writing process, studied other authors, and attempted to improve as a creative and analytic writer I've gained a certain measure of authority. I don't think it's so great, but I have some knowledge. And I've even called myself an author-in-training on this blog. So if I say that writer is one step away from author in my mind then I suppose that calling myself a writer is valid, though slightly overwhelming.