10 years ago by
A Pianist
Don't worry, your reply is not overly long at all! It is full of valuable information which allows me to understand and guide you better!
Everything you are doing is right, it is all really excellent - but it is not enough. You need one more ingredient to get yourself over the hump.
Getting your bones into standing position where they are lined up is great, but if you achieve it solely through relaxation, this good position won't hold up under pressure. You need to cultivate more overtly the actionof the hand, specifically whole finger grasping, not curling the distal joint. These two styles of finger flexion ideally work together, but to learn whole-finger grasping better, I would advise you even to lay off finger curling for awhile and learn the empowering sensation of whole finger grasping by doing it in isolation. It is this action that will remedy the subtle, almost invisible collapse that has been troubling you until now.
Good luck, you are a fine pianist. If you learn this you will be an even better one, both technically and artistically. Whole finger grasping opens up your tonal palette tremendously as well as improving your physical technique.
AFF