If you are already using Exiftool Gui (as you suggest), check the Maker tab and look for the "ShutterCount" tag. I added that tag to the Custom view because there is so much to scroll through .
Some exif viewers may call it "Actuations". Photomechanic comes to mind.
I'm surprised you are not seeing it in your raw files. Never heard that before. I shoot raw only so I usually need to look at my raw files because most image editors and browsers strip that out of JPGs they may make. I don't have a D800 but I get raw in my D2h, D200, D700 and D300. I've used Opanda to get that tag, and now use Exiftool/Gui because it appears to have a more comprehensive list of maker notes.