I love
Emmanuelle! It's one of my all-time favorite girls names. Personally, I think
Emmy is the best nickname, and I've never thought of it as being particularly cutesy.
I don't mind that its pronunciation is basically the same as that of
Emmanuel. I've always thought that
Emmanuel sounds feminine to begin with.
Other possible nicknames are
Manu (delightful in French) and Noelle/Nuelle?.
http://www.behindthename.com/pnl/177263