You might very well be carving too wet. And wetting too much during will bring all the nice relief out agin ruining your work.
If you have to re-wet, wring out a sponge well or MIST with a spray bottle and wait a few seconds. Wipe off standing water if it collects.
I think that you are not cutting deeply enough and your beveling isn't in the cut line on many places. Let the leather come to almost the original color before cutting. If you need to re-wet, make sure that its the leather that is too dry and not your knife that need stopping!
Try a few pieces of scrap of the same oz. leather and really get into it. Don't cut all the way through!- but cut a lot deeper than you have been- maybe 1/2 the thickness. Background when it's a tad bit drier.
Also know that for things like a holster where there is a bend involved, it will tend to push out the tooling a bit. DON"T carve a wallet, checkbook, etc where there is a sharp fold. It looks bad, but worse, it "breaks" the leather. Make your pattern such that it can accomodate (eliminate) folds and creases.
Hope this helps.
pete