Mae Whitman was 4 in When a Man Loves a Woman when she played the character 'Casey Green'.
That was over 30 years ago in 1994.
This was her first recorded movie acting credit (although may not technically be her first actual acting role).
Today she is 35, and has starred in 69 movies in total, 69 of those since When a Man Loves a Woman was released.
In When a Man Loves a Woman, I think Mae Whitman looks: