Here's another name that you are probably more likely to find on a child than a living adult, but would not be too weird on one (never dropping out of the U.S. Top 500): Amelia. This name has skyrocketed in recent years (#30 last year, and even higher in some other countries) after being last popular in the late 19th century (which was the era that a famous namesake of this name, Amelia Earhart, was born). Despite being easily usable on her own, there are several nicknames you can get out of Amelia:
Amy - Although now in the "mom name" territory it's not too much of a stretch even these days, and will probably have a bit of a retro feel to a modern girl.
Mia - Another name that's climbing the charts on its own, Mia is also a not-too-stretchy nickname for Amelia if you want something longer to go on the birth certificate.
Millie - A nickname with a similar antique charm as Amelia herself.
What do you think of Amelia, both without and with these (or any other(s) you can think of) nicknames that you like?