This is book number 1 in the Planet Pirates series.
Old enough to be used Young enough to be broken
Sassinak was twelve when the raiders came. That made her just the right age: old enough to be used, young enough to be broken. Or so the slavers thought. But Sassy turned out to be a little different from your typical slave girl. Maybe it was her unusual physical strength. Maybe it was her friendship with the captured Fleet crewman. Maybe it was her spirit. Whatever it was, it wouldn't let her resign herself to the life of a slave. She bided her time, watched for her moment. Finally it came, and she escaped.
But that was only the beginning for Sassinak. Now she's a Fleet Captain with a pirate-chasing ship of her own, and only one regret in her life: not enough pirates.