How to be addressed

I’d ask your officiant. He may have an opinion on it. If he doesn’t then I’d think Maggie would be fine.

Formality in print is one thing. But if people know you as Maggie, it is fine to use that when speaking to you .

I think for the lighter side he can do “Maggie”. But if it is a formal service “Margaret” .... or he could be “Maggie____. ____ and do you Margaret take ___” kind of thing. So the final serious wording is the formal name.

My nickname is Jai & I'm having that officiant do that because I don't use my real name Jaimie unless it's for work or government reasons (DMV, banking, etc)

I put my nickname "Alex" on the Save the Dates and my formal Name "Alexandra" on the formal invite. My officiant will address me as Alex, except for the actual vow part.

I think Maggie is what you are comfortable with then that is what you should do as it is your wedding.