Looking good OP :)
I am so far from being an expert that it is not funny, but I do have some suggestions...
Try riding with a neck strap (can be a polo wrap, thin piece of leather or an old stirrup leather - which is what I use) you can use it to hold onto to aid with your balance and keep your hands steady while you are learning. I use one on any new horse and whenever I jump. My instructor introduced me to one at the start of this year as I told her I wanted to improve my balance... I now love it. Hated it at first, it was the biggest PITA, but it has helped so much. gkvid.jpg
As has been said before, you are sitting in a bit of a chair seat. Try and sit to the front of your saddle and imagine that you are trying to touch the ground with your heels from the saddle. I find it helps me keep my lower leg position, it should be under you and not move as you post.
For your two point... do a lot of core strengthening exercises! And also some work without stirrups to work on your balance and lower leg. If you are not balanced in two point, it makes it harder for your horse but also it makes it almost impossible to stay on if something happens (a trip, spook, buck, refusal, etc) My legs and core would ache after a lesson! Two point without stirrups is evil!!
It should look something like this... but better :) gkmurraysj.jpg
Not like this... haha My balance is horrible, my two point is horrible, my feet aren't under me... GK rushed because he was unbalanced (hence the circles), chucked an extra stride in the double, catlept and..... I fell off. https://www.youtube.com/watch?v=-zB4KkXNZdA
Glad to say that I don't ride like that anymore... But please let me be a cautionary tale of what can happen if you have no balance in two point!!
Keep up that hard work and you will be surprised at how much you can improve :)