@Anonymous69 She doesn't have "Transformation" magic. Her unique magic is "Creation" magic. And whether it lets her make a potion or something that lets her change genders, it'd probably cost an absolutely absurd amount of MP to create it. I don't doubt it's possible, but if she wanted a certain bit back, it'd probably be easier to do that alone than a full body change.
Also, she does Create clothing, but as stated above, her Creation magic has an absolutely horrible Cost ratio. She starts buying fabrics and stuff just to keep those costs down. One of her big things is just spending time making food and clothing. Her Creation magic at that point is more like a crafting menu with scaling MP costs depending on her level of knowledge for the process, materials she provides, and how much she's done of it herself.
A lot of comments here seem to think every isekai protagonist needs to have some grand goal, but for the most part, it's just a lot of food porn rather than regular isekai shenanigans. I guess the only overarching plot is them trying not to be found out by that ugly merchant.