The Flair system and Wow saddles - help!!

[HashRouge]

My arab mare is very awkward to fit, because she has a naturally round tum, flat shoulders and is croup high. However, I purchased a WOW saddle several months ago and, with all the different girth options have finally found something that will stay in place. However, I've recently noticed hollows on her back where the back air bags sit - forwards of this is fine, but then the muscle seems to drop away.
I'm quite worried about this, does anyone have any ideas about what might be causing it, or what possible solutions could be? My saddle fitter is already coming out because one side of the saddle appears to have more air in it than the other, but I'm really starting to lose faith in her and would like some extra suggestions.

[CER1389]

Pictures would be helpful. She certainly shouldnt lose muscle with a wow. If anything you notice they gain muscle.

Which girth attatchment have you found which holds it?

[HashRouge]

I'll try and get some pictures done tomorrow.
The saddle fitter tried the fore girth, but that led to the saddle leaning forwards, so she is now using what they call a 'H' girth. I believe it was brought out very recently.