My assessment had forms to fill in before hand which helped, there was a scale form with a list of symptoms that asked me if I experienced a symptom and to rate it and a second form with a list of symptoms asking me if I experienced a symptom and if so to give examples of it, as well as a third form for someone who knew me to fill in.
I felt that this allowed me to more effectively communicate my issues as answering and speaking can often be difficult, especially when it concerns mind-related issues.
When I had my assessment with the psychiatrist he still asked me to tell him what was up in my own words before we discussed what I had written and whether I had ADHD but the pre-assessment forms help me so much especially as I STILL struggled to organise my thoughts during the assessment which the psychiatrist picked up on.
If I were you I'd get a second opinion. I live in the UK and spent years (like over 10 years) in the NHS mental health system, it's awful and I eventually went private and it was the first time I ever felt anyone had truly listened and taken my pain and struggle seriously.