Try to lengthen the stirrups.
Then take your feet out, point your toes down and try to draw lines in the sand with your toes. This will pull you in the right spot in the saddle. Do that ever so often while you ride until you get a feel where you should be. Once you have that spot, you might find the stirrups a Tad short again
There's not a darn thing wrong with this picture, judgeing from what I can see from that angle:
In this picture
You do have a chair seat. It looks like you are pushing yourself back into the cantle with your feet. So, rather than riding DOWN into your stirrup, you are pushing them OUT and away from you.
The length, in my eye, is fine. But, you probalby have a somewhat locked knee.
I like the excersize of using your toes to draw in the sand. But, before you do that, try this:
Sit in the saddle with horse standing quietly. If horse is not calm enough to sit still while you do this, then get a person to hold the bridle.
Bring your feet out of the stirrups and up in front of you so that they rest on the horse's shoulders, heels right up as high as you can get them , right on the horse's shoulders. Try to still sit up as straight and proud as you can, even with your legs hiked up like this. You should feel your seatbones pressing very hard and directly down intot the saddle. Sitting up nice and straight, looking ahead, lower your legs til they hang straight down. NOW, try drawing with your toe if you like. The way your seatbones are now is where they should be all the time.
Now, just lift up the front of your foot until you can hook it onto the stirrup. Keep letting your leg hang down.
Once you find the stirrup, try to keep the contact with the stirrup just about what is needed to keep your foot from slipping off. And never, ever lock your knee, It must be able to flex so it can absorb the hrose's movement.
FWIW, I believe in riding the saddle. What I mean by that is I want my rump in the lowest part of the saddle, and I want my legs wherever they need to be for the stirrup leather/fender to hang straight. When that happens, gravity becomes my friend and tends to keep me there.
If I want my legs forward or back from that position, I have to put tension in my leg muscles to force it to happen. And that is fine, at times. For a tight turn, I like my heels all the way under my hip. At others times, I may want them more forward. But if I want my legs relaxed, then I need to let gravity position them, and where that will be is determined by the saddle maker.
I don't compete or show, and I'm not a trainer of anything. But what I wrote makes sense to me. If it doesn't work for you, toss it!
"It looks like you are pushing yourself back into the cantle with your feet. So, rather than riding DOWN into your stirrup, you are pushing them OUT and away from you."
Agreed. I sometimes do that with Mia to help keep her focused straight ahead, but my ROT is that bracing and tension is bad, and relaxing and loose is good.
You need to roll your pelvis as the horse canters and relax your legs to keep yourself off the cantle. In the pic on the bridge, shift your hips forward an inch or two and bring your lower leg back an inch or two. There's an old coaching epression, "nose knees and toes" should form a straight line. They will if one could hold a stick at your shoulder going thro your hip to your heel.
I took a lesson at my barn and the instructor dropped my stirrups down a hole and had me to the feet-on-horse's-shoulders exercise. I don't have any pictures, but she said that my chair seat was long gone. :) Thank you everyone!