Yes seems quite confusing.. sometimes you wish the airport might blow its' own trumpet about passenger figures, if they are good!
From what I can see using Terminal and Transit passengers pdf from CAA website there were 11841 terminal passengers and 1299 transit passengers, which equals the 13140.
So if we use the 11841, and minus the other routes figures (including the HUY,LBA etc figures) this leaves 3045 to go to Aberdeen, which is around double last year. In Loganair's press release they said they were carrying 66%, so 2000 with Loganair and 1000 with Eastern/Flybe.