[1] She went on to appear in a variety of leading and supporting roles in German and Austrian television, films, dramas and European cinema.

In 2010, she starred in The Coming Days alongside Daniel Brühl and earned the nomination for Best Leading Actress at the German Film Awards in 2011.

Alexandre approached Heerwagen, then aged sixteen, and asked her to play the lead role in his new film for German television.

After landing a supporting role in ARD and Bayerischer Rundfunk's television film Liebe und weitere Katastrophen (1999) alongside Senta Berger, Heerwagen was then cast as the co-star in the German television two-part film Der Schandfleck (1999) which brought her to much wider notice as an actress in Germany.

In 2004, she was cast in the central role of Miguel Alexandre's film Grüße aus Kaschmir for ARD and TV-60 Filmproduktion, for which she won the Best Actress award at the Adolf-Grimme-Preis in 2005.