I think thats why men go wrong sometimes as they apply the same kind of force to themselves as to a women say when rubbing their clit which will kill the mood instantly lol!
There is always a bit of ball sucking, sometimes men like that, though obviously these you do have to be sensitive about! Not sure much else you could do, does humming work while you do it, obviously don't be like humming a Buble song or something 
If your tied up he could possibly use you more, using your bust or butt checks to rub himself between?
Looking into his eyes, appreciative noises when he's working on you should spur him on more.
Think your getting there? maybe think about a waspie or something in future so doesn't have to be unpicked necessarily, though I thought some have side fasteners instead of ribbons, don't forget the heels and seamed stocking lol
He should be pretty appreciative of this !