Do you mean Meghan instead of something like Meg? On the form I did since it's part of a job application and shortened versions feel unprofessional. In daily life? Just about the only person I hear my name from these days is Miriam and she calls me Meghan and it give me no end of joy. I was talking with someone I've mentioned before, Train Girl: she started calling me Megs, and I kind of liked it.