Another possibility is that your name is related to the Scottish name Michie, which is often pronounced like Mickie, which could easily have been transmuted into Mackie where your family lived. Here is a brief description of the origin of the name which I found online (at this url:
http://forebears.co.uk/surnames/michie), quoting from The Surnames of Scotland (1946) by George Fraser Black:
Quote:
An Aberdeenshire surname found mainly in Strathdon, Glengairn, and Crathie. "The name," says the late Dr. Alexander Fraser of Toronto, "is a local diminutive of Michael, and the family is a sept of the Macdonalds of Keppoch, descending from a Michael Macdonald of that branch. A fairly exhaustive enquiry establishes this fact. In the Aberdeen registers the name and its variants are traced to 1570, before which date Michael MacDonald settled in Aberdeenshire. The chiefship of this sept was in the family of Corryhoul, a place occupied for more than 200 years by them, and now represented by Lieut. -Col. John Forbes Michie, Toronto, who, only three years ago, disposed of the last of his ancestral rights in the old home" (Celt. Mon., XXII, p. 159). John Mychy was tenant of part of Morton, 1473 (Cupar-Angus, I, p. 170). David Mihie had a son baptized in 1606 (Aberdeen Jour. N. & Q., I, p. 99). As forename we have Michy Nycholson, 1446 (Cupar-Angus, I, p. 128)