That's why I said you can edit this a dozen ways, but good lighting will always make this better SOOTC.
I agree with everything you have touched on in your post, just wanted to help with an edit to further push an image past what it was currently at by the OP.
Yes, I totally agree with you cconner, as you stated, "Good lighting will always make this better SOOTC" (straight out of the camera). I just had a few minutes, and thought I'd write out a few thoughts about why this photo looks flat, and why the original poster titled the shot, "Feeling like my portraits are a bit flat." The title of the post made me think that the OP was uncertain about why the portraits (plural) seem to be a bit flat.
If a person is new to studio lighting, and turns to the internet for suggestions, there are HUNDREDS of self-taught people doing lighting videos that show this same, cross-lighting set-up as being "the way to light with umbrellas", or whatnot. A few years ago, even Canon USA's instructional manuals diagrammed a two-light speedlight flash shot with this same type of cross-lighting, and even MIS-identified the lighting ratios. This was all covered in Chuck Gardner's on-line lighting blog, complete with an article discussing the poor lighting Canon itself was showing, and the mis-identified lighting ratios. SO...even "reliable" sources sometimes prove to be full of baloney in this, the internet age.
One of the most difficult things to overcome is poor instruction in the fundamentals. With so many people being self-taught, and learning on their own, at home, alone, and often using speedlights in umbrellas, with no modeling lamps to guide them, learning how and where to position the lights is many times a total,total crapshoot.
Today, we have many people who are attempting to learn very challenging things "alone", at home, in what I call "self-teaching". A lot of people get all bent out of shape when I use that phrase, self-taught. What I mean is that when a person learns "alone", at "home", without a mentor, without a really experienced teacher, that he or she is at risk of learning how to do things from other people who really are not all that experienced themselves. Cross-lighting set-ups are all over the internet, and this is what the OP is doing. Not assigning any blame, but pointing out that this method of lighting is GREAT for killing shadows, and making things like docments look perfectly flat, and one-dimensional, and it a good way to light when the goal is a flat, dimensionless recording of something like a watercolor painting that is to be copied and then made into a photographic copy print, or whatever.