To me they look a bit to long because when you post you have to go on your tippy toes. I would shorten them 1 or maybe even 2 holes. I like my stirrups to feel like my heels are down, and if I had to I can go over a jump (not jumping length, just the feeling that I wouldnt be stuck in the saddle if my horse went over a log or something)
I think your position is quite good, just make sure your thumbs are on top of your hands, not at a tilt, I know, it feels pretty to keep them at a slant.... (or maybe that's just me... lol) but it doesnt look good at all compared to thumbs on top! :)
And keep your hands closed ;) I had that problem too, but trust me, its nicer for the horse to have hands that are closed instead of just open.
If there are no horses in heaven... im not going.