That was over 6 years ago in 2015.
Today she is 31, and has starred in 48 movies in total, 9 since American Ultra was released.
In American Ultra, I think Kristen Stewart looks:
American Ultra scores 6 out of 10 on The Movie Database.
Kristen Stewart's first acting role was as 'Girl in Fountain Line (uncredited)' in The Thirteenth Year, released in 1999 when she was 9.