im confused on when your lowering amount of frames in the beginning . are you following a set amount each ? or winging it ?
The amount of frames for each bounce depends on the distance it is falling/bouncing.
The further it has to travel, the more frames it will take. But remember, the spacing will always increase on every frame on the way down.
Start with your first drop - say if it takes 14 frames to fall. Then the next bounces will have to be less than that (14 frames was only 1 side of the bounce)
The bounce after that will also have less frames until it stops bouncing.
There is a little bit of 'tweaking' the physics to make it look better than real life, but it is all based in reality. The physics you setup are in that first drop.
I hope that helps, Cherico.