Your leg needs to come forward in all the pictures, mostly in the first two- A little more release, too. You seem to be throwing yourself forward, and not moving with the horse's jump. Try to bring your heels down a little more, so your feet aren't flat in the stirrups. I have to agree, gypsygirl is right. Try to find a trainer, and do some more ground work to get your legs where they should be. Find some books with exercises to do, I know there are plenty of books out there to find- I have a book of exercises from ground work to courses that I like a lot. I can give you the name and the author if you want, I just need to find it first haha.
But to balance this all out, you're good for a self-taught rider- I just think that you've done what you can by yourself, and now to progress you need a trainer who has much more information and experience to give you. :)