I'd like to see your legs come underneath you a bit more on the flat. Do this by opening your hips and relaxing your lower back. You are focusing on your horses head set too much. I can tell because I have the same problem. Focus on not just looking up, but looking ahead as well. In most of the pictures you don't have enough of a contact on the reins- nor is it even.
You have very soft hands, which is always good, but there is such a thing as too soft. It's when you barely have any contact at all and there is a loop in the reins.
As previous posters said- you swing too much with your posting trot. My guess is your posting from your lower legs and heels rather than thighs and stomach. Posting correctly will be extremely beneficial for you and your horse.
You also have puppy dog hands, but I will not go into this, since you stated that you know.
Your shoulders-not your back- are hunched. This may sound (and probably will) sound very.. inapropriate, strange, awkward, and your probably going to wonder what's wrong with me. Here goes: try and remember to "flash those headlights" as my instructor says.
Also if you wear a polo: put a needle, tak, etc. in the back of the collar. When you feel it poke you, you're straight.
I'd also like to see you putsome more weight into your heels.
You get ahead of the horse's motion just a bit. Think about sliding your butt back to the edge of the saddle. Not standing up in the stirrups, but folding at the hips. You stay in the same position, and as the horse jumps it comes up to you, and back down. This is where confusion comes in when teaching yourself, or if you don't have many jumping lessons. You see tops riders, and they stand up out of the saddle, and it looks like they do so much with their jumping posistion. Well once one gets to the higher levels of jumping, you do shorten your stirrups even more. But not until well after 3'6". Also you tend to 'drop' your reins when jumping. It's good to give a generous release. If you drop the reins, however, it will often lead to the horse refusing, running out, or a very slopping jump (cause from rushing it because of dropped reins) and a very sloppy landing (caused by dropped reins in the landing), and speeding up after the jump. This will lead to a bad second jump.