I wouldn't tell her right off the bat that you are autistic, but you could explain that Autism Speaks' emphasis on prenatal diagnoses and cures is simply going to lead to autistic people being discriminated against, etc.
The less emotion the better. She might find it more appealing that you are able to hold a cool and collected conversation.
Good luck! I'm sure you can do it.
_________________
Your neurodiverse (Aspie) score: 134 of 200
Your neurotypical (non-autistic) score: 72 of 200
You are very likely neurodiverse (Aspie)