I used to like
Megan, until it became megapopular. But only in that spelling. A double N makes no sense and nor does an H. Meggie is an odd nn, come to think of it. Forget
Megan for a moment:
Margaret used to shorten to
Peg or
Peggy or
Maggie. Not Mag. And it seems wrong for
Megan to shorten to anything other than
Meg, and certainly not Meggie. Megs, maybe!