I would have an honest conversation with your therapist about how it makes you feel invalidated when she says stuff like that. If she brushes it off and doesn't take it seriously, I would just tell her that you think that you are done with seeing her for treatment and ask for a referral for a different therapist. There's a good chance that she will say that in an attempt to validate your feelings, but that it doesn't come across correctly. If that's not the case, she'll brush off your concerns and then you know for sure that she doesn't care.

It sounds like your therapist may not understand how you feel about this and you should explain that her comments are fueling your imposter syndrome. But if I may provide some insight, she likely is trying to explain to you that while you're autistic, you're not alone and people who are not autistic can still understand to some compacity what you're going through