How to explain possible diagnosis with 10 y/o - and where to start?

Hello, I suspect my 10 y/o daughter is autistic and I'm looking for advice on 1) how to start the process of getting a diagnosis 2) whether it's necessary and 3) most importantly, how to explain it to her or get her on board. It's something I've been exploring and mulling over to myself, but haven't yet broached the subject with her at all for fear of upsetting her at what is already a sensitive developmental age.

She is bright and articulate and generally does really well at school, however over the past couple of years I've increasingly noticed she is lagging behind her peers in terms of basic independence and in navigating social dynamics. She also has some sensory challenges that get worse when she's anxious/tired, and struggles with changes to established plans to routines. Because she "passes" most of the time and performs well at school I am on the fence about whether we need a diagnosis at all. However, I do feel like our entire family life revolves around her sensitivities and moods, and sometimes her behaviour causes problems in her friend group - it could be helpful for her (and me!) to be able to make sense of her difficulties.

She generally responds badly to any suggestion of seeing a doctor for physical issues, so I'm nervous about having the conversation with her - and would like to have a potential appointment set up for if/when we do discuss it. Any advice on gentle words to use to explain my thinking to her and present it in a positive light?