Hi, Elizabeth.
I'm a model as well. I use my full name, AND my nickname. The full name sounds formal, while the nickname makes me the sixteen year old that I am. I would suggest using Elizabeth AND Elle, or Elizabeth AND (other nickname), to show that you are versatile. The full name makes you sophisticated, while the nickname shows your spunk. Hope this helped!
P.S.- Do you have a comp card or business card? I would suggest, if you do, to put both names on it. For instance, mine says Caitlin "Cait" Surname. Just a suggestion!
Good luck with everything!