I tend to agree with jumanji, but based on the top photo where the shoulder angle, just visible on the offside, is a lot flatter than the angle of the tree point. They should match - if the tree angle is steeper the saddle will pinch.
You should get a rough idea if you fit the saddle then slide the flat of your hand hand between horse and saddle behind the flap. If it slides under easily something's causing it to bridge, and the tree width is the first thing to suspect.
Please bear in mind this is a very, very rough guide to tree width. It depends on how far up the panel is fixed, which can vary slightly between individual saddles of the same model, never mind from manufacturer to manufacturer. A lot of people measure dee ring to dee ring, which is just as variable :(