I was talking with the voices in my head and we got to the topic about Gilly "not liking" to dress up. I see that, in the book, contless time it was said that she didn't like to wear dresses and was allways with messy hair and when I was younger I had that same vision but, thinking about it now:
Gilly is a kid, I know she's 12 and almost a tenager but still a kid, and she was raised with a lot of siblings and parents that worked a lot. She didn't had a example of someone that was frequently wearing expensive clothes or make up and the people that she saw as and example of those things were also the people who, in her vision, ruined her life, and that's something that is clear in the book since she allways compare well dressed people with royals (she did that with Alva, with Flora, the RLW and even Anna at some point).
Also, as I said, she have lots of siblings, 5 younger ones at that, she was mostly playing with them and babysitting them so obviouly she would prefer to wear confortable clothes and shoes and eventualy get used to live like that, what doesn't mean that she can't learn to enjoy wearing party dresses when she gets older. Other point is about her uniform being a complete mess most of the time, but, guys, she's 12. "Oh but the other crew kids aren't like that and they're her age". AG and Jocelyn have other people to do fix it for them, Maxime, Kayla and Haley pronably take better care of their clothes so they are ok during the classes and Jax and Ollie probly get their uniformes fixed by someone at the Royal Maynor who works for Jax, what leaves Gilly as the only one who have to do it by her self and doesn't care about it.