Okay, so 10 years ago MC was a Royal Bodyguard. That ended when the Princess she was guarding became Empress. That's interesting, and part of me wonders if her post as a General was basically an unofficial "Promotion Exile". I wonder if Emperor dude realized that his new wife had come down with Sudden-Onset-Lesbian and so got rid of the source.
As for keeping their past hidden; Guys, this is an age before Photo IDs or anything like that, set in a world inspired by Imperial China which was, how do you say, Focken' LARGE. The first chapter explicitly states that no-one in the Army MC lead had any idea that The Dude was even a part of the Royal Dynasty until the day he left. Considering their army was being sent out for basic Rebel Control against a force only 3000 strong, MC wasn't some really-famous general. Hell part of Dude's way of bribing her was pointing out that she would probably never get the opportunity to command large armies in major battles except via this method, indicating again she isn't considered anyone special in the military hierarchy.
Even if you did find someone who knew her like the fanboy from chapter 1 and brought them here they might not recognize her because she's the Fuckin' Empress now. She'll be caked under so many layers of Make-Up she might as well be wearing a literal porcelain mask.