I don't think that just becasue the horse was anxious to move out it is any indicattion that the saddle doesn't fit. the sweat pattern indicates an even fit, and in the photos, there is nothing glaringly wrong.
I will say that you are so small, for that large of a saddle. It ends up having you too far behind the center of the saddle, resulting in your pelvis tipping forward, and your leg pushing out in front of you.
I would recommend three things, if I may be so bold:
1. Use a better quality , wool saddle pad. you will experience less sliding. That saddle pad is a POJ (piece of junk).
2. Look into a 'seat shrinker' from Cashel, because that saddle seat is too big for you. It will help you fit that saddle better, yet is removable for when your husband rides Duke
3. Put Duke on a diet. I know he may be a Kiger, and an easy keeper, but he is PHAT!!!
I hope I have not been too bold.