Its a cracking shot as it stands, Rob.
My first thought was down the traditional route, ie rule of thirds, and the subject should have been more to the right of the frame with space on the left.
However, given the lady is looking straight out of the photo and that great smile means there is only one place you are going to look and I think a square crop would work well.
Dave
Great image, wonderful processing
Too over processed for my liking.