My first "Portrait"!!
Thanks so much for addressing this area - distance to subject! I think you were typing out that you usually are at least 8 feet away from your subjects? You missed the most important part of your sentence - the number of feet! But I think, based on your advise that I move back an additional 4 feet, that I can safely assume you meant to say 8 feet. And that would help both with the distortion while automatically increasing depth of field. And yes, I'd have to crop a bit - but as you say, that's perfectly acceptable.
Question - you mentioned adding a small fill card to the flash. Is that a reflective device that would sit ( in this case) to the side and a bit below the model? To toss up some light from below? I've heard a cheap and inexpensive product is those car windshield reflectors - I don't own a proper reflector yet, but if I continue to do portrait shoots I think it's likely a "must have".
I don't want to achieve immortality through my work. I want to achieve immortality
through not dying. (Woody Allen)