herethere, I think that's interesting that your daughter does that. I (33, a woman) felt very much the same about "girl stuff" at that age. Violently rejected it, wouldn't play with it, only wanted boy toys, boy clothes, would throw a serious full fledged tantrum over a skirt.
It took me a long time to understand that I was basically parroting the misogyny society had fed into me. I was rejecting girls as social groups, girls as friends, and "girl stuff" because I could sense the way it was denigrated all around me.
When I did "boy stuff" and pushed away girl stuff, I got so much approval from men, and I wanted that approval pretty desperately. I knew how men treated "girly" girls and how they were viewed, and I wanted to see the look of respect and "the kids are alright" I got from them when I told them I was building a rocket. I knew how much social currency there was in boy activities, and how very little there was in even the most dedicated, skilled girl activities.
When I was that age, I knew that boy clothes weren't designed in a way that made you wonder if you were showing something you didn't want to be. I knew that girl clothes were for a group of people who wanted to be called "pretty," because as soon as you wore nice ones, people started talking to you like all you were was "prettiness."
Yeah, there can be something beyond just being a tomboy. But I'm looking at my child and am very glad I didn't destroy my fertility by getting sterilized, or spend years in a blind panic because I believed it was truly important for everyone in my life to change the pronouns they use for me.
I identified with boys because I was told by everyone I listened to that boys were full-fledged human beings and girls were basically icons or inspiration or purely aesthetic, social creatures. I didn't want to be a caricature. I wanted to be a person. For a long time, I thought that meant being a boy.