@Wolfwhistler the author made it so that the character just enjoys dressing up as a young lad because apparently, our MC enjoys, looking at girls, too. It would be weird if a girl would do that and I truly think that our MC just enjoys being treated as a man. Remember how much she was restrained when she introduced herself as a woman, how many were jealous because she was a woman. and how a crown prince from a strong country just wanted to take her by force as his concubine/woman not even as his wife just because she was a pretty girl.
She LOVES her curves. Don't take me wrong. She loves to be a woman but HATES the behaviors, expectations, and looks men and women do when they know she is a girl. Remember that every time she goes to new places she has a better treatment as a young man and people don't expect her to behave in a certain way just because she is a girl.