Is it worth getting a diagnosis?

Hi, I believe I have Autism as does my psychiatrist and my friends. I am on the NHS waiting list which could be a few years wait time. I am having help from my psychiatrist and have read some helpful books. Is it essential to get a diagnosis or should I carry on as I am as my treatment won’t change whether I get an official diagnosis or not so not sure whether to put myself through an assessment incase for some reason they say I don’t have it and it’s all in my head…..