You don't deserve to ripped apart, you look awesome for a newbie! And correct me if I'm worng, but in the pics you look like a boy, so kudos to you!
Ok, like yolu said, you should pull you're shoulders back and sit up more, also, of course your toes. It also looks to me like you're hunching your back and leaning backwards over the jump. Try leaning a little more forward, letting your back relax a bit, and collecting your horse before the jump. Great job, you and your horse look cute togethor(sp?)!
” You know you’re a horse person when you walk past someone and instead of saying ‘excuse me’ you poke them in the ribs and say ‘over’ “