The high-key look, the model's pose, the full-frame composition, the focus points and the hair, make-up and clothing all combine to give an air of innocence and simplicity to this image.
I am not 100% sure it needs the grain in the shot but that may be a result of camera settings rather than aesthetic choice and - of course - my personal taste. There are no rules.
I also feel that there is not a huge amount of story in this picture. That's fine - not everything needs a ton of story in it after all, some things are just beautiful to look at - but I feel that the opportunity was there. Perhaps it is all in her look which is genuinely complex (congratulations to your model as well as to you for that
) - and, of course, beauty and story are both always in the eye and mind of the beholder of a photograph. As the photographer you can reach out, fill the shot with your intention and have it fly over the head of the person viewing, for no reason at all.
So, in summary, this is a lovely piece of work, well executed and effective. It's a simple piece and none the worse for that - excellent stuff!