Well I don't jump but from what I can see, first please let go of your horses mane, if you can't jump without holding on, then don't jump. Your legs are really far back and your strups are to short. You toe looks like its about to come out of the sturp so I wonder how the landing was on this jump, again im really not a jumper, I just call it as I see it.
I think this rider has a very nice, flat back. Her eyes are up, which is more important than holding or not holding onto the mane. Sometimes holding the mane to stay out of the horse's way is ok, and alot of the times more humane. Even the most educated and able riders sometimes have to grab mane, it doesnt mean you aren't capable.
To help this rider's stability a bit better, her leg shoulder be a bit more underneath her. Her lower leg thrown back is caused by pinching of her knees. Secondly, if she were to just scoot her rear back towards the back of the saddle it would be easier for her to get balanced over her feet.
Otherwise, this rider looks like a brave confident rider, and her horse looks happy which to me is most important. :)
What I see is a rider who has minimal balance but a lot of confidence. It seems as if you just threw yourself out of the saddle and hoped for the best.
You should be hovering over the seat of the saddle, legs underneath you. Your upper body looks decent.
I personally think you should go back to the basics. Work on your two point. Can you balance over your saddle? Are you sure? Can you let go of the reins and raise your hands above your head, to the side, twist your body, etc. without losing your balance? Can you do this at all 3 gaits?
Then i'd go back to jumping very small jumps. Do the two-point you've been working on over the jump. The major things you need to improve on is getting your legs secure and underneath you and working on not jumping ahead.
Also, kick your stirrups back to the ball of your foot. It'll help you with your balance.
OK, its not a fashion show and wear whatever you want, its not people's job to judge you on what you wear if you're not showing =) All I have to say is that your hands are a little far up the neck but I would definitely hold mane, especially if the horse takes a long spot/overjumps because then you don't catch them in the mouth. I don't think there is anything wrong with holding mane over a jump to you don't get pulled back if you're not ready. And for the lower leg its pretty far back but try to not pinch with your knee and do try to wrap your legs areound your horses barrel to keep them in position. And I think your stirrups are fine, its easier to get yourself out of the saddle and off their backs/out of their way like that. Good job and keep up the good work!
Don't take this the wrong way, but you perched on top of the horse and if it stoped you'd fly over the neck and break your leg.
This is down right dangerous and any careless mistakes and you could get seriously injoured- which means back to the basics, you can't jump before you can keep your leg in the right place in a two point.
Go to youtube and search maclay finals and you'll see how to fix your balance
On the plus side your back is flat and your looking up, keep that up!