I would actually say that your helmet is too large.
I hate to say it really I do especially after seeing all the work done and what a beautiful piece it is. It look too long and too wide.
However, this may be a fixable situation.
As for the face being too long, if it's possible to add a bit more dome padding to raise it even 1/2" and still be able to see, I think will balance it alot and rid the turtle neck.
For width, this was an issue my brother had with his. We simply bulked the shoulders up. Youf shoulders are quite bulky but, they ride right against your shoulders. If you padded the interior with 1/2" of padding inside each shoulder, that would add some width to your shoulder girdle.
Those combined should balance the helemt to torso.