Hi Sophie,
I've had two graduations. The first time, i read the bit where they suggest you wear a button down collared shirt and thought a dress would suit me much better. On the day I had no where to attach the sash to and the way the robe fell sort of made my upper half look like I might not be wearing clothes underneath it!!!! The second time I wore a button down collared shirt as they suggested and the outfit worked and looked much better. So please consider wearing a shirt like they suggest!