Thorisdottir went through all Norwegian junior teams beginning in 2008 at under-15 level. She was part of the under-17 team during 2009 UEFA Women's Under-17 Championship qualification and was called up to the finals in Nyon, Switzerland where Norway finished in fourth place. A year later, she was again part of the under-17s as Norway proceeded to the second round of 2010 UEFA Women's Under-17 Championship qualification before losing out to Germany.