Star Compass (Victoria Eternal #1) by Anthea Sharp - SPFBO 2020 Book Review 03, Oct

Diana Smythe was born into the nobility, but after a tragic accident she ends up living as a streetrat named Diver. Her exceptional ability to calculate mathematical trajectories gives her an advantage as a pickpocket, but it will never be enough for her to achieve her dreams of escaping Earth. Or so she thinks, until things take an unlikely turn when she helps to avert a terrible disaster at the Spaceport.