Can you guess my main character's age?

I joined a contest on Brenda Drake's blog where I put the first 250 words of my manuscript on my blog and then people will come to guess her age and critique my work.  Friends please feel free to join in on this too :)

The bell on the door jingled as I ran into the diner. I was a half hour late for work and Uncle Don hated when I came in late. I had told him that I was going to go to the doctor's this morning and that would make me a little late, but he still wouldn’t be happy. Uncle Don hated any kind of change, and that was the main reason why I still worked here. I started working at the diner when I was ______ and really wanted to get an MP3 player. My parents decided it would help me “build character” to earn it on my own. My Grandpa had just passed away and Uncle Don was one of Grandpa’s oldest and dearest friends. I think we both wanted to feel closer to Grandpa and we helped each other through it.

The diner was relatively small. There were six booths and there were twelve stools at the lunch counter that backed onto the kitchen. Uncle Don, as always, was in the kitchen stirring up something delicious. Everything in the diner had a sixties feel to it. I don’t know if the feeling was kept on purpose or if the diner had not been remodeled since then, but either way it felt homey. As I walked through the diner I saw most of our “regulars” sitting at their normal booths. There was one woman who I didn’t recognize sitting at the counter. Granted I only saw a mass of black hair since she had her head down.

Thanks to all who participate :)  and follow me please...I promise I will return the favor!