It sounds like your are trying to get your glove on shots that you should be handling with your arm, shoulder, or chest. This is a "side effect" of having active hands, which is a great thing, but sometimes it is very hard to catch the puck in the pocket if the puck gets in tight to the body. In those situations, it is best to seal the arm against the body and absorb the puck in the c/a.
If the shot is not in any danger of being tipped or redirected, sometimes you can shift your center as the shot is taken so the puck will hit you more square in the chest instead of at the spot between arm and body. It is these "in-between" shots that sometimes handcuff goalies and produce bad rebounds. Note, this re-centering isn't meant to be a push into the shot (this could lead to trouble if the goalie moves before the shot is taken!), just a small adjustment as the goalie is moving to make the save.
If you are producing cuff rebounds on shots that are away from your body, you need to focus more on getting the pocket of the glove out into the shot.