Hachlaf was born in Khénifra, and began her international career at an early age, competing in the 800 metres at the 2003 World Youth Championships in Athletics when she was fourteen. She qualified for the semi-finals but did not manage to finish the race. She had greater success at the 2004 World Junior Championships the following year, as she recorded a personal best of 2:06.44 in the heats and reached the event final, finishing ninth. In 2005, she entered the IAAF World Cross Country Championships for the first time and was 31st overall in the junior race. At the 2005 World Youth Championships she won her heat and recorded a season's best of 2:06.91 to finish as runner-up in the semi-final behind Teresa Kwamboka. She failed to repeat this form in the final and was fourth in a time of 2:08.61. At the end of the year she competed at the 2005 Jeux de la Francophonie, and won a bronze medal in the 4×400 metres relay.