A lot of the problems in your position can be stemmed from two things - one, you're sitting too far back in the saddle and two, you're not sitting correctly. Rather than sitting on your bottom (which is called a chair position), you need to roll onto your pelvis and bring your leg underneath yourself. You're perching because you're lower body isn't able to support you correctly.
I think if you sat more deeply in your seat, rolled onto your pelvis, than riding in a chair position, a lot of things will start to fix themselves and you'll be able to feel so much better in the saddle!
I like your wee mare too :)
Hope this helps somewhat!
♥ Seoul Searchin' for the Lovebug ♥