A few little suggestions?
In the first picture, her hands are resting on the top of the horse's neck... try sliding them down just a smidge so that each hand is resting on each side of the crest, it will give her a little better release, and the horse might round a little more over the jump. Also, she looks just a tiny bit ahead of her horse, I do the same thing all the time. I have to sit back when approaching the jump, a litterally tell myself, "wait, wait, wait" so that I'm not jumping the jump befor the horse. Believe me, it will make a difference when you get to larger jumps!
The second picture, she looks a little flat and stiff, maybe the horse was jumping flat, it was hard to tell. She is definitely ahead of her horse. Her heels look down, but her leg position looks weak. It looks like this was one of those jumps where you just kind of go with it and then say after, "what on earth did I just do?" your back should be straight, but not forced and stiff. Your head should be up, but not looking at the clouds... Always remember to look at the next jump, that's how I remember to look up and ahead, without looking way up. Again, I think this might have been an "oops" jump. Or maybe the horse took off to early, stretched to make it, and the rider was forced to just hang on for the ride. A++ for effort, but if not, then try focusing your legs to stay on the horse, always driving forward. Also, try to imagine your body is built with springs, and not bones and joints. Nothing should be stiif, nothing should be forced. Don't arch your back or shoulders, don't push your legs and heels out so far that you get "locked up".