Please, spell it
Megan. There are waaay too many ways to spell this name, and keeping it as
Megan makes it so much simpler. I've known people who spell it
Megan,
Meghan,
Meagan,
Meaghan, Meighan, Meegan,
Maegan, and even Meaghanne (eww!). It's kind of like
Brogan. The spelling
Brogan is so much nicer and less of an eyesore than, say, Bhroghan.