Almost not so much the missing elbow as that side of the frame is too close to her face. Since she is looking out of the frame to that side, you could crop closer to her right arm (that's a nice vertical line you can get pretty close to with a crop) and leave the left arm in to give her a place to gaze into and out of.
This is a lovely shot Kathy, I would agree with Jocelyn though and I would crop it just a little more to remove the hand in the bottom right corner. :D
I agree with Mike @mikehamm not that I am any expert at portraits as I haven't explored this subject. But since she is looking towards her arm our interest peeks and it would be good to see more or the arm. I thing you caught this yourself. But I must say I love the innocence in this capture and the touch of pink in the background brings balance to the photo. If I were to imagine I'd say she is waiting with anticipation for her prom date.
