In 2002 she won the Women's World Darts Trophy, beating Karin Krappen in the quarter-finals and then Francis Hoenselaar in the semi-finals before beating Crissy Manley in the final. She also won the British Open Ladies Singles the same year. A year later, de Boer was the youngest competitor at the BDO World Darts Championship in Frimley Green and reached the semi-finals, beating Linda Rogers-Pickett in the quarter-finals before her run was ended by Ladies World Champion Trina Gulliver.
In 2002, she triumphed in the Women's World Darts Trophy, defeating Karin Krappen in the quarter-finals and Francis Hoenselaar in the semi-finals before winning against Crissy Manley in the final. She also won the British Open Ladies Singles that same year. The following year, de Boer was the youngest competitor at the BDO World Darts Championship in Frimley Green and reached the semi-finals, defeating Linda Rogers-Pickett in the quarter-finals before her run ended by the Ladies World Champion Trina Gulliver.