I can see where thief is coming from, but I'm leaning more towards Monk as well. The fact that you mentioned being fair, loyal, kind, and more modest all remind me of monks. People in the monk class are at times more calm and serious, but many of them are cheerful, and kind people. You particularly remind me of monks like Zell, and your more tomboy-ish nature also makes me lean a bit more towards monk.

Edit: had to add my team :]