Welcome to the Forum!!
To me the saddle is a tad forward of where I would like to see it...otherwise... Its not a bad fit.
Wither clearance seen.
Not seeing a "pinch" of to tight with it just sitting there.
I would not be using a thick saddle pad myself but a thinner pad or doubled blanket if that.
To much padding will make the saddle pitch and pinch.
Wish you had shown a rear forward facing picture so we could see how and where the gullet lies on the spine better...
It is not only how the front of a saddle sits that makes a fit or not...
It is how the entire saddle sits and fits the horses shoulder, back, spine and sides that tell the story.
No saddle fit standards exist today so brand to brand sizing can change and does.
It can be trial and error finding a fit that works well, but your mare is not a strange shape or exhibit things that would make fit difficult..
If you can go to a saddle shop, sit in a few saddles that fit you then ask that store if they can bring them to your barn for a horse fit... a serious potential sale can make a lot of good happen.
Or, ask if you can trailer the horse to the store and have a safe location/place to unload for trying saddles and you would like to sit on them and ride a bit cause it feels different sitting on a wooden horse versus the real thing moving under you.
Major saddle companies have saddle reps who are decent at fitting saddles, just recognize they are going to push their products..
You can find that with fitters too if they are affiliated with any companies and get a kickback or perk from selling a particular something or other.
Stores know when and what days those reps will be at their store or they can arrange a time and date if seriously looking/buying will result in a sale.