First, the saddle is too far forward. Second, she has a pretty big shoulder though it doesn’t come back too far. I think she is wider than you think she is. The saddle is too high in the front. I suspect if you cinched it down, the back may pop up. I think you need a little saddle with a higher gullet for her withers, fairly straight through the back and flair for her shoulders.
What do you want to do with this horse? Have you tried any barrel saddles on her? Unless you are roping, try some barrel saddles on her or whatever kind of meets the above comments. A roping saddle or some ranch saddles may be too low in the pommel once you get it to fit in the shoulders with her withers. A cutter would work, too. Once you decide what doesn’t work, then you can figure out what does. If that makes sense.