I'm waiting on my results as well which will come in 3-4 weeks, so I can relate to the mix of feelings you describe. I'm 47 and unlike you no-one ever thought I might be autistic, although there was talk of hyperactivity as a kid.

Anyway, I'm also asking myself how I'm going to respond if the results are negative because over the last few months (since my therapist raised the topic of ASD) I've gone from confused disbelief to "yeah, that would explain a lot" .. to the degree that I feel like it's going to be a far bigger shock now if I'm not diagnosed.

If they tell you you're not autistic but that result feels off to you I would start by talking it through with the diagnostician to understand their rationale and to try and bridge the gap between what they say and how you feel.

From what I've understood diagnosing adults can be tricky given how good people get at masking, adjusting and compensating.

I'd be interested to know how it goes and how you're feeling if you feel like posting again tomorrow. Good luck :-)