It depends on your style of riding. Your stirrup looks nice and long enough, but if you are doing half seat riding, it should be a bit shorter.
Roll your shoulders back and down and really have a nice soft bend through your elbow. Turn your wrist so that there isn't a break between your forearm and your hand.
Hands up just a little, they should hover over her wither but no farther back than the pommel of the saddle.
I feel you should tilt your pelvis more to face upwards so it's more of a driving seat so that you don't have such a large dip in your back.
Your head seems to be craning/reaching forward. Relax and make sure it is square over your shoulders.
"Strength is the ability to use a muscle without tension"