I played an exhibition match against Mike Sigel many years ago and he commented that I had a tea cup grip. I think it's similar to the grip you describe. Daylight between the cue and my palm. Makes the wrist sort of wiggly, but I believe this is where much action is achieved. I know I tighten my grip but also know I never go into a full grip as in swinging a hammer. To me the full grip freezes the wrist in place. I remember asking Mr. Sigel, oh is that bad and he said no, lots of good players use it! Good luck!
I totally agree!