benifits of diagnosis??? Help

Hi all, I have a 9 yo dd who I have suspected from babyhood to be on the spectrum but Iv ignored and tried to manage symptoms on my own (badly). She is high functioning but I wonder if there are any benefits in seeking a diagnosis when she has no learning disability or physical impairments. she is a high achiever at school but I just am worried that I don't have the knowledge or tools for her as she enters her teens.