Sandy

6D
85mm
32 inch Octa

The histogram in LR and can be seen here.. it's bunched up to the left but if I try and spread it out, it just looks blown out even before it's officially blown out. What's the issue??
Just a poor exposure

To my eye and taste this is a perfectly fine exposure and an overall excellent shot. I'd be inclined to bring up overall exposure just a bit and blacks a bit more but would use care in not messing with your overall image.

I think it's just reflecting the overall darkness in the composition... dark background, dark clothing, and she has a dark tan.
It looks perfectly exposed to me.

Exposure is actually great. Maybe add a silhouette light on the left side slightly behind the shoulder. You can use the curve to adjust exposure without over-exposing.

Skin exposure looks great, maybe just bring up the blacks a pinch.

I am no expert, but I see nothing wrong with this portrait. Everything, from her jeans and shirt, to the background, to the exposure of her face, looks appropriate. Personally, I wouldn't change anything. Not every photo should have a widely spread histogram. In this photo, the lightest part of the scene is her skin, and her skin looks well lit, to me. You can't have a histogram that looks any different when a scene looks like this. I think this is an excellent photo just as it is.