Sounds like the stirrups are too short, but also, you're going to want to try a lot of different saddles before you buy one, and yes, a saddle on a stand can feel very different from a saddle on a horse. The way the seat is made, the type of swells, how high the back is, any of those can change how a saddle sits.
But... you really, really need to have a horse first or else you're really just window shopping. ;)
PS I'm 5' 9", 200 lbs, and ride a 15.5, but I have to let the stirrups out to a length most men ride to get everything positioned right.
Afterthought: Like Beau... what kind of saddles are you trying out? Who's the maker? A barrel saddle feels different from a roping saddle feels different from a trail saddle feels different from a reining saddle, etc.
"We are here to laugh at the odds and live our lives so well that death will tremble to take us."
Last edited by AtokaGhosthorse; 04-09-2018 at 12:15 AM.