Thanks for the suggestions! I appreciate it!
That's the thing, Tinyliny, I'm not sure if the saddle is bridging or not. Her current saddle pad has an even layer of dirt/hair etc over her back, with perhaps the smallest increase in nasty in her wither area, but it's very very slight. To my eye, looking at the saddle and looking at her back, logically I say it should bridge since her back seems curvier than the saddle (which is very straight) but the saddle pad says it doesn't... I do know that she does round her back significantly as she moves, so perhaps she's filling in that space? I'm really not sure. And the tree of the saddle is forward enough in the saddle that to be placed correctly behind her shoulder, the saddle/saddlepad itself is not going to be on her shoulder really at all.
I don't really understand how that saddle does what it does, maybe it's because it's "old" (made in 1969)? But it really doesn't want to work like most of the saddles I've ever come into contact with...
Here's a picture of about where it wants to sit on her back (sans saddle pad, and probably half an inch too far forward still, imo, since the tree starts right at that first white leather "concho" thing):
I do agree completely that if it is bridging, I need to pad more in the middle and not over her shoulders/withers. I'm just confused as to whether it really is bridging or not. And I really appreciate your input, I don't mean to sound like I'm full of excuses! :)
Also, I found the pad I have and apparently it is an inch thick, not 3/4, so that's a relief! It must be 1.5inches over her withers that makes me feel like I'm riding a barrel... At least the 1 inch pad, plus a saddle blanket is way too much padding. Lacey doesn't mind at all but there's no feel for her back, just roundness.
I found another pad that might fit the bill... It's not a swayback pad persay, but it is thinner in the front, enough that it looks like her shoulders will be in the thinner part, and then it goes to 1.5 inch thick in the middle. It also looks like the transition between the thin to thick part is tapered which adds even more to the freeing her shoulder part... And the back is contoured like the swayback pads I've seen, where the back end of the pad is shaped as well as the front... However, it only has three stars out of 5 but it won't let me see the reviews so that makes me feel a little goosey about it... Weaver Contoured Western Saddle Pad - Horse.com
What do you think?