"I'm trying to relax my hand and just let the string go but don't have it down yet.Any advice?"
Thats the idea, but it seems you stop pulling and thats where the collapse at release comes from.. Remember you never totaly stop pulling, even at anchor and increasing back tension, before actaully rleasing is a positive thing.
Try thinking of it in these terms: after I commit to the shot, I'm gonna increase back tension and move toward my conclusion and sometime during that move, the back of my hand is gonna relax a bit, but I'm not gonna think about my release, only increasing back tension and reaching my conclusion.
Conclusion can be anything you like, as long as it takes longer to reach than it takes the arrow to clear the bow1 Mine is my fingers touching the shoulder...yours can be anything you like.
A lot of guys shoot very quick and to a degree, that works for a lot of folks...one thing I'm sure of..if your train to shoot a good deal slower, you can always speed up if needed ! Watch the HH tapes...HH could shoot very fast, but when a shot called for a higher degree of precision....he could slow his shot down and take as long as the shot required...and thats what I strive for, the ability to become slow and sure when shooting at tiny 11 rings and to have the abilty to speed up and shoot a buck thats only gonna pause for a split second between to saplings, or on aerial targets.
clear as mud?