Honest and True

What's wonderful is that even before I read your comment, I spent a minute looking at the interesting facial expression. It's one that makes you think "I wonder what she's thinking?" After reading the comment, I realized that it's the look someone gets when they forget about themselves for a moment. You can't get more relaxed and natural than that. There's what looks like recalling happy memories mixed with a current longing for more happy memories. A mixture of wistfulness and awe.
There's another thing, and I'm not sure why this is, but the hand seems to balance the tilt of the head, and actually adds to the emotion of the face.
Whatever you were thinking in that moment, it was an excellent choice.

(I'm not sure how to rate modeling with the star system, so take them with a grain of salt)