Overall you have very good position. Back flat, eyes up, legs solid underneath you.
However, in the two last pictures it appears that you've got the 'chicken wings'. Try to keep your elbows in at your sides at all times, even when going to a rollback. You don't need to open your rein that much over a fence to get him to there, just stay solid on the landing and turn where you need to go.
I also noticed that it appears your jumping slightly ahead of your mount, as you are just about above the front of the saddle. Try to wait more, and let the horse's natural jump bring you out of the tack. With jumps of this size, you don't need to make such a big effort as it seems your making.
Your toe is slightly pointed out, its not too huge of an issue, but may cost you a placing in Hunters if they're really picky. Just try to roll your whole leg around so that your inner thigh and side of your calf are on the horse, which will bring your toe facing forwards. It will also keep your heel from accidentally hitting the horses side as it is probably doing in the position it is in those pictures.
That is all I see, you have quite a solid position! Just a little fine-tuning, that's all.
...he's so kissable, huggable, loveable, unbelievable...