I like your lower leg and base of support in both photos. In the first photo, I like your upper body position as well. You're in balance, but your eye and shoulder are up as you prepare for the drop. The objection I have with your release in the first photo isn't that it's floating, at this level and over these types of obstacles that's fine. My objection is that it's a little restrictive - I'm basing that on how much of the bit I can see out of the sides of your horse's mouth. You could have either brought your hand and arm further forward in your release or slipped the reins more; I would prefer to see you carry your hand and arm more forward/out of your lap ; then slip the reins when you're in the landing trajectory.
Second photo shows same good lower leg and base of support, perhaps too much angle in your hip for the size of the fence, though I'm allowing for the fact your horse looks thrusty and round. Your upper body is definitely a little too close to the neck.
Your release looks a little restrictive in this one too, judging by your horse's face being behind the vertical. Try releasing by dropping your hand down a few inches as well as forward a few inches. I also sense some tension in your shoulder and arm in this photo, which makes me suspect you lock your shoulder and elbow when galloping to your fence, and then have difficulty allowing them to follow the motion of the horse's neck over the fence. That could also be the reason for the upper body being to far forward - if your shoulder and elbow are tense or locked, your upper body tends to follow your hand and arm, rather than functioning independently. Might be part of the bad habits left over from the rushing mare.
I very, very much like the look of your horse. Looks like he/she is a blast to ride cross country, and has some jump to spare.
Best way to work on your release is to set up some simple gymnastics in the ring that allow you to focus entirely on your position and not on the fence. You should definitely work towards dropping your hand lower/more toward an automatic release and get comfortable with the idea of your elbow opening and closing and allowing the hand and arm forwad.
Finally, look at some video or have someone watch you galloping cross country and see if you stop following or lock your hand and arm on the approach.
It's a pleasure to critique such a capable rider and horse.