How do you work through the worry of getting a diagnosis?

Ive been on the fence about trying to get a diagnoses but Ive been nervou to, and its not because im worry about being autistic or anything but because Ive heard some truly tragic stories of people just getting treated like crap by medical professionals. And I myself had a pretty bad experience back when I was 19 trying to maybe get a ADHD diagnoses/seeing if I was neurodivergent in some way, where after I tested borderline on the self assessment for ADHD the psychologist told me I couldnt have ADHD because, get this, I had good grades in high school. That statement just gutted me, especially with how much I struggled in high school, getting a 3.8 GPA was the best GPA I had during my entire high school experience and I was so proud of myself and having this psychologist just slap me across the fact with it broke my heart. Especially when I knew how much work, time, literal tears, when into getting that 3.8.

So anyways, my question is just how do you get over that fear and worry? I dont want to be treated like an idiot or be invalidated again, or do I just need to suck it up and push through?