DD (13) identifies as LGBTQ+, certainly gay, goes swings and roundabouts about being NB and at the moment is testing out being called by a different name by her mates. I slightly doubt that she is really NB (I do think some people are, but very few), but want to have a sensitive conversation and not rubbish her. I wouldn't worry but she's starting to say she has moments of feeling sort of 'weirded out' about her gender when she looks in the mirror and I want to communicate to her that it's not something she really needs to worry about IYSWIM, and I don't want her overthinking and overcomplicating stuff for herself by thinking something's a bit 'off kilter' when it isn't. I have already told her she has time to work this stuff out and to try not to stress, and that she can express herself how she wants regardless of her sex.
At the moment, she still respects my opinion 
, and she knows I have trans friends and family I support. I feel like I just want to let her know that adolescence generally can be full of difficult, ambivalent feelings about our body and our selves. She has some NB friends, including a close one (S) who is having a turbulent time of it and I want to tell her that I know she is empathetic and cares about S, but she doesn't have to 'take on' M's difficulties, and to maybe ask whether spending the mental energy on carrying different pronouns/name would be less stressful for than owning her existing ones? Is it something she really feels she needs? I can say safely I have never identified with the idea of what being a woman is like in popular culture (I don't at particularly match the archetype in women's media), but I do feel secure I am a woman and have never been upset by feeling I don't fit the my supposed 'gender role'
Does this seem like a reasonable angle to take? If she has issues with her image of self, she should talk about them, but I'm not convinced gender identity is a useful vehicle for dealing that and could cause unnecessary stress to her.