The Angel and the Ghost (Fortica Chronicles Book 1)

Eliza, a seventeen year old slave, is a micron- a human with control of millions of microbots that all live in her body. Using them, she is able to escape the Mexica and flee in a spaceship to the dangerous New Life System. Once there, she finds herself taken in by a band of other microns, who plan on using a unique code stored in her body to travel back in time to bring the Mexica to their knees- despite any damage they may do to the space-time continuum.