? 6%?

I get 17.5 % body weight loss.
2800 - 2309 = 491
491/2800 = .175357, so ~ 17.5% loss from Aug.
That said, her weight may have been abnormally high in August (inflammation, retaining fluid, etc, etc, etc...) and she may be somewhere around her normal now???? I know you don't want to handle her, but I would gently feel her breast. Any movement on her by your hand should move in the direction of feather growth. (i.e. like on back, stoke from head to tail.) I know you will be very gentle....I would be nervous about the weight loss and would need to feel her breast/breast bone for confirmation of either 'okay' or 'needs more food'
But, that is me, and I tend to be a bit impatient and need to 'know now'....You are a bit more contemplative than I...so please don't take my need as a directive for your action.