you can move the saddle forward, but it will shift back into the position where it most closely fits the shape of your horse's back.
a better saddle pad might help your horse's comfort , some. it depends on what they fit problem is; too tight? too loose? too long?
Would you be able to post a photo of your horse with the saddle on, WITHOUT any blanket on? and take photos from various angles, in good light.
you will see that there are many threads about saddle fit on this forum, and looking at them will give you an idea of how to photograph to give us the best view.
I see that you are in Columbia, no? so, the saddle used may not be familiar to many of us in N. America, or Europe/Australia . . but, general fit should always be more or less the same.
Bienvenido a Horse Forum!