I should say, IME dressage saddles emphasize the horses movement, so you can really FEEL what they're doing under you, so you may simply be noticing the movement more so it feels bigger. Not to mention dressage saddles are designed to put you in an ideal dressage position, so if you don't typically ride like that, you will be using different muscles, and using different parts of your body to absorb shock (I.E. hips absorbing more shock, compared the ankles and knees like in a jump saddle).
In my mind, tucking your body to sit the trot isn't quite ideal, so when the dressage saddle put you on your seat bones more and didn't let you curl, it made it harder because you aren't used to using those muscles? Ideally you want to sit straight up, engage your core, and have your hips "bounce" (flex) with the horse, while the weight of your shoulders keep you in the saddle. Meaning your hips, and to a lesser, but still noticeable degree your lower stomach/ core come up and forward (at least on really active horses). Rather than curling and pushing down or trying to flatten yourself into the movements (the opposite of the sitting trot ideal for dressage).
Also, dressage saddles can sometimes (depending on flocking and seating) make a horse feel much bouncier (one brand I swear made a QH type mover into a trampoline).
The deep seat or longer stirrups could have made you feel more insecure if you tend to curl your body or rely on your leg to keep you stable.
One final theory is although jumps saddles should hypothetically free up the back and shoulders more (to allow the horse freedom of movement over jumps), they often do not, whereas dressage saddles tend to do so better. So perhaps the jump saddle was restricting your horse, and this dressage saddle fits better, and therefore allows for a bigger, more free movement.
There are a million things it could be really, the saddle could just not fit you, causing you to feel weird. It may not fit your horse, causing her to move unusually. In my mind though, you probably just aren't used to riding in a typical dressage position and saddle, making it uncomfortable. That being said, I also think the saddle probably just doesn't fit you well (can't really say w/o seeing you in it), but the blocks, seat size, twist, flap length, seat shape, ect. just may not be right for you.
I would say make sure the saddle fits BOTH of you, if it doesn't fit you, your discomfort will affect your riding, and therefore your horse. And if your horse is uncomfortable, she won't be able to perform well, and could be in pain.
I will agree with tinyliny, a video or at least a picture would help a TON.
Anyway, there are a SO MANY great saddle fitting videos (for both horse and rider) that you can do at home (w/o calling out a fitter) on youtube. The Schleese website has free articles on saddle fit (Schleese are considered saddle gods pretty much, I would love to have one but they are super expensive).
Good luck! I hope all works out well for you and your horse! :)
Last edited by elequine11; 06-04-2020 at 12:23 PM.