Whatever happened to Katie?

Substitute teacher for Monday and Tuesday in choral. The one for yesterday-Monday-was a total bitch. Anyway, she called my name on the attendance. "Katie?"
I pause. I don't usually hear that name in school. The only other teacher who calls me Katie is the art teacher, and I don't mind it from him. But she said my name, and there was a silence. Everyone's face assumed the "Who?" expression, and I answered that I was present. I didn't bother to tell her I'm called Kat, because it wasn't worth it. Sarah, a fairly nice person, said "Your name is Katie?"
"It's Katherine," I said.
"Katie?" she repeated.
"Yeah," I said. "Katie." The word sounded funny. Foreign.
"It doesn't suit you," Sarah smiled at me. "You're not a Katie."
I kind of shrugged, but inside, I was quite troubled. My whole life I've been Katie. Maybe not at school, but in my family. And Katie looks like such a cute word. I see the old photo of me at age six, decked out in pink with crooked teeth and purple framed glasses askew on my nose, and shiny blonde hair in two plaits. Yeah, that's Katie.
It hurt me that Sarah said I wasn't a Katie. I mean, she didn't do it intentionally, but still...I've had a lot of names, and I am everyone of them. Katie, Kat, Kate, Kathy, Katherine Chocolate Eclaire...there was one Spanish girl in fifth grade who called my Kitty or Kit, because she couldn't quite say Katie, and the Italian lunch-lady, Angie, called me Katarina.
Katherine means pure, as do all versions of it. Right now, I'm Kat, and for the most part, I like Kat. Who will I be in ten years? Katherine? Who knows? But I still have to wonder, what happened to Katie...