All that said I rather like the image.
I believe in the 1 light can do a lot rule, but in this case with such a dramatic scene I would have had a separate light for the background, and one for her clothes and one for her body. At least 2 lights, its hard to do EVERYTHING with one light and doubling the duties of a head can have issues such as this. I think you would have been better off with a beauty dish. If you notice with that there is a center disk that blocks the direct light if the bulb itself so you probably should have done the same with your open octagon. Even just adding a diffusion gel just in front of the head would probably help.
I wasn't there so it's hard to tell. Now a days I've been taking one wide shot of my setups so I can reference if something goes wrong.
Mamiya: 7 II, RZ67 Pro II / Canon: 1V, AE-1, 5DmkII / Kodak: No 1 Pocket Autographic, No 1A Pocket Autographic | Sent w/ iPhone using Tapatalk