It helps to be open about the fact that you tend to mask your symptoms, compensate for them--that you work very hard to make up for some things that seem effortless to others.

The way I first mentioned it to my psychologist was to mention that my mother had recently told me that if I had stayed in school, they would have tried to diagnose me with Asperger's, and that's why she pulled me out. (I disagree with this decision. It caused me a lot of grief. But she meant well at least.) If you had some similar clue that led you to consider whether you might have had a missed autism diagnosis, mention that.