jobun: "She is presently on life support but is brain dead. My question is pertaining to her soul. did her soul leave her body, or is it still tethered there since she is technically alive in body only
At present her body is still functioning albeit to a very limited degree from what you've said. We have to assume that if breathing support were withdrawn her body would stop functioning because it appears there is no brain activity. As I view the situation the tether between body and spirit - the so-called silver cord - will still be intact and her spirit will still be associated with her body, albeit perhaps very tenuously. If/when breathing support is switched off I think her body will die and at that point her spirit will become totally free.
, or is her soul stuck in a transition?
No nothing is "stuck" but she has yet to complete the transition from incarnate to discarnate life, to complete her 'passing-over'. She's not stuck but she's still not completely free of her now failing body.
I'm really upset about this and pray that she isn't stuck somewhere in between life & death."
Of course you're upset, totally understandably because it's horrible state for her to be in. But she's not trapped in some 'no-man's-land' situation although I expect she'll be aware of what's happened. I would expect her to be eager to complete her transition.