You have a wee bit of a chair seat. Bring your lower leg back, so that there's a straight line from your head to your hip to your heel. I'd also bring your stirrups down a hole or two. There are a couple pictures in which your shoulders are a bit slumped, but others in which they're back, so I'll assume that you're working on that on a consistent basis. Also, bring your elbows in. In a couple pictures, they're out like chicken wings! ;) You look like a good, confident, and experienced rider.
A little tip for the leaning on the bit madness (Mudpie had a big problem with this) – When he leans on the bit, drop him. Just for a moment, and then re-establish contact. That way he learns that he cannot lean against you. Just push your hands forward briefly. He may lose his balance, but that's the point. He doesn't rely on your hands for balance, just like you don't rely on his mouth for balance! :)
As for your boy, I think you should work on collection a bit. It would help a lot. ;)
Love him, and you two look like a good pair!
The hills were bathed in moonlight, the shadows not so stark;
Silver light reflected off his brown hide as he held me in the dark
– I love you, Mudpie!