Trying to make this clearer:#1
Here's a BCC document (forget the white area, it is part of the BCC window document background):
The light green area at top and light image area at bottom are the bleeds area.#2
The layout is a 85 mm * 54 mm card set in portrait:#3
The green background is set with negative offsets (here -5 mm):
So, I have to make this background shape (a rectangle) bigger adding, two times, the value of 5 mm for each axis: width = 54 + 5 + 5 = 64 mm and height = 85 + 5 + 5 = 95 mm. Note that I've choosen to make the green background covering the whole card, even if it is partially masked by the flower image. This is a personal choice.
I use the same principe with the flower image:#4
Then I export to pdf with bleeds set to 3 mm (0.125" in your case):#5
Opening this pdf in Preview (just as a way to verify the pdf dimensions):
(forget that dark grey area, it comes from the Preview document window background)#6
Dimensions of this card with bleeds = 3 mm:
Width = 54 + 3 + 3 = 60 mm
Height = 85 = 3 + 3 = 91 mm
(yes, it seems that there's an (rounding?) error of 0.1 mm)#7
The same example with bleeds and cut marks (cut marks are not always needed by printers):
Hope this helps.