I suggest 2 actions:
1. Run WinDirStat
. That will tell you exactly whats on your disk (but not the shadowstorage).
2. For the shadowstorage, go to Start > Computer > right click and go to Properties > System protection (in the left pane on top) > System protection tab > highlight the D drive > configure > and what is the number behind "current usage" in the second half of the window?