Stern first represented Switzerland on the international stage at the 2012 Winter Youth Olympics where her team of Michael Brunner, Romano Meier and Lisa Gisler won the gold medal. In 2014, she played in her first World Junior Curling Championship as the alternate for Corina Mani. They lost the tiebreaker 7–6 to Sweden's Isabella Wranå. She returned the following season at the 2015 World Junior Curling Championships, this time as lead for Lisa Gisler. Her Swiss team won the bronze medal. In 2015 she also played in her first European Curling Championship as alternate for Alina Pätz. She did not play in any games. Stern returned for her third consecutive year to the World Juniors at the 2016 World Junior Curling Championships. She skipped her team to a 4–5 record, missing the playoffs.