You are actually supposed to be able to fit either a fist or three fingers between your butt and the saddle front and back. A hand is too big. I unfortunately had to find that out the hard way when I was told a hand in front and a hand in back, and I ended up with a HUGE saddle that in no way shape or frame fit me, but because I was in pony club and that was what they said, no one mentioned it looked to big until I had the chiropractor come out and do a saddle fit with my Arabian, and she said that the saddle was way to big for me, forget the horse for the moment. I have since found a better Crosby saddle that definitely fits me better, and fits her nicely.
That aside, if you shorten your stirrups a bit, and sit up straighter, in a more proper position, I think that saddle actually fits you pretty well. It may be a TAD on the small side, but not enough to warrant trying to find a new one. BTW, I absolutely love your horse. She's so cute. If she goes missing she isn't in my barn ;).