I really like the third photo, it caught a nice moment in your work, it's a shame it's a little dark.
In this photo, she's moving up under herself fairly well, is accepting the contact and moving into it, and has an appropriate bend for the size of the circle. She also looks happy and relaxed. This is a good example of a young horse beginning to learn to use herself and work correctly.
As far as your position, it looks as though you need to "find your seatbones" - it looks like you're sitting in the back of your saddle, rather than sitting in the middle, balanced over your seatbones. It also looks like you have a tendency to drop your inside shoulder; it's even more apparent in the fourth photo, where it looks like you've collapsed your whole left side as you've asked for the bend. I would also like to see you bring your hands together, and carry more bend and weight in your elbow, but I understand with a young horse just learning to accept the contact, this is a work in progress. Do also remember to focus your eye up and between her ears, this will help the dropped shoulder.
I won't critique the first two photos, I'm guessing they're from early in the lesson when you were warming up as she's above the bit and resisiting.
Keep up the good work!