I saw your picture while I was visiting my mother. She has taught many many to ride, and the first thing she teaches is the half seat/two point for balance as a prelude to posting. She liked your position very much. You do have contact with the horse's sides and you are not using your horse's neck or mouth for balance. Understandably, your foot is too far "home" in the stirrup but that will improve with better fitting boots.
If you search online for the George Morris book Hunt Seat Equitation and scroll down through the pages, you will see your body postion in the half seat/two point is not far off from the picture he uses as a model. I believe I've seen poster bsms post the picture I'm speaking of in past posts.
Bernie Traurig explains the different seats that could be utilized in a course, and that it is important to be able to use them all. 5 Minute Clinic with Bernie Traurig