That sounds about right actually nykole360. Without getting too technical, a good rule of thumb with english saddles is when you are sitting in the deepest part of the seat, you want a handspan between your tush and the back edge. You also want to be sure that you get a saddle that puts her knee on the knee roll if it has one, or centered on the flap. Shorter legs actually make that the trickier part of the fitting. You probably need to stay away from anything with a long flap or a forward flap. The easiest thing is to go to a tack shop that has sample saddles, or consignment saddles, and have her sit in them to get a feel for what is right. You could likely get some help from the staff in that regards as well.
"Keep a leg on each side and your mind in the middle"