You could always have the incident be something that happens when she's already in the military after having more training. She's on leave at home when the war starts and the attack begins. It would also make more sense for someone who's already a trained soldier to survive such a situation. 

I would also add that the Turian defensive forces wouldn't buckle and retreat so haphazardly. Doctrine states that they'd hold out as long as possible before attempting to withdraw in good order, covering the retreat with traps and a strong rearguard. It wouldn't be a everyone for themselves dash.