From the first pic it looks like your a little perched in the saddle and a little tipped forward. (Difficult to see from the angle though!) Really concentrate on relaxing into the saddle with your shoulders up with your tummy sucked in to help you sit a bit more upright. To help you to sit a bit deeper try some work without stirrups, concentrate on letting your hips and legs relax and hang as long as possible.
The jumping pic looks good, you look as if you weren't in front or behind the movement, your giving with your hands nicely so your horse is jumping nicely and looks like he's enjoying it. Only thing is the stability of your lower leg,try your stirrups up a hole or two and see if it helps. As you jump, try to think of it as lightening the seat not standing up. Imagine you're sitting on a £50 note and you don't want to loose it as you jump! Yet you need to remain light in the saddle so your horse can bascule nicely.