OP what makes you think you’re not? This post is autistic AF, as someone autistic.
I’m very high masking when I choose to be (sometimes when I’m not… it’s sort of automatic by nature at times) and in a lot of cases people never know. I was in my 30s before I figured it out, and I used to use the saying “I’m not autistic but” a lot.
There are free tests available. AMA (not a pro but I have over 30yrs experience!)
I was diagnosed with autism at a young age, but that actually turned out to be a different thing (xxy), so I no longer have the diagnosis. So it’s still possible, but not probable, more likely partly a result of xxy and not autism.