the world it lives on needs a denser atmosphere and lower gravity, its wing muscles are way too small for earth. On large fliers the wing muscles start to make up a larger and larger portion of the body mass, square cube law is unforgiving. the largest animal to ever fly is larger than your dragon but also almost all wing muscle. on the upside the overall size of the wings seems good.
Ask yourself how does my dragon fly, is it a glider or strong maneuverable flier, this will tell you how much muscle it needs.
here is all the muscles on the wing of pterosaur not counting the flight muscles.
Your dragon has very cat like but has no reason to be. Its limbs are shot but powerful, yet completely useless for hunting, they are built like cat limbs, but if they try to roll around with prey like a cat they will destroy their wings, and they are far to short and angled wrong to be used in fight.
Its body is way too long and flexible for a flier keep in mind everything is essentially hanging from the wing shoulder in flight, fliers want to be compact and need a fairly rigid body, mammals are fairly weird in having a lumbar region most animals just have ribs all the way down. This makes the body stiffer but can also support more wing muscle. look at a birds, bats, and pterosaurs, shot compact bodies. long thin bodies make for good swimmers or climbers not good fliers.
Birds are probably your best model since unique to birds many birds still retain good ground locomotion, but bird wing muscles may not be a good model since they have both sets of flight muscles on the ventral side which is unique to birds.
If it is horse sized the neck is too long and weak for its head, a predator with a big head wants a necks that is shorter to support strong muscles for it, or it can have a small head and a flexible neck. lower gravity may help but you still have many competing hunting styles in the anatomy.
Ask yourself how does your dragon hunt. Does it attack from the air or ground, does it kill with claws or teeth. Remember a big animal with wings cannot rolling around with its prey, so don't use cats or crocodiles as a model.
On the other hand horns and crests are fine, both birds and pterosaurs did this grow large ornamentations on the head, but keep in mind they should probably be hollow.