3 days to go. What will happen.

Hi all. I have my formal diagnostic assessment on Tuesday 5th June. I’m really nervous. I have spent the last year coming to terms with Autism being the reason I am who I am , and I am quite content and at peace with that. But I still need it confirmed by a professional to be totally at peace. But what if I’m not autistic? What if its OCD or ADD? That would totally throw me! My longsuffering husband is coming with me. Can anyone tell me what they will be looking for, or what kind of things they will ask. Its a 3 hour appointment with a diagnosis at the end.