Joey's Mom

I am a special education teacher and have had some experience with Autism. Over the last year, I have thought my nephew might have some level of it. I have observed and tried to push my sister into putting him into daycare or a preschool type program so that maybe someone else would see and if needed he could have services. Of course she did not want him to go anywhere, she is a stay at home mom, saying no one could really work with him. She had no idea what I thought and thinks nothing is different about him. My son and hers were born 13 hours apart and are worlds apart in learning. They will be 3 in September. these are the symptoms. When asked a question even as simple as what is your name, he repeats it back to you. He does have some on own talking but it is very basic. He does not handle loud noises, change, new foods, new clothes, shoes, etc. well. When given these things, he screams a high pitch scream and doesn't stop until all is back to normal again. He is brilliant with his letters and numbers and shapes. Been able to identify by naming since age 2 (early 2). Doesn't really play with others, still in a sort of parallel play. Plays with toys but most of the time anything with wheels or puzzles. He lacks eye contact and does not really hug when he is hugged. Smiling happens but when he wants it and is not frequent. Out of frustration and love,I guess, i suggested to my sister to get him checked, because of my background and his behaviors. Of course she was defensive and now is cold when she talks to me. I don't know if she is going to do anything. She has made a call or 2 according to my mom, but is telling the doctor not the full truth when it comes to his behaviors. I just wanted her to get services if they were needed because there is so much out there. I also talked to my ped. and he said if nothing else he has a delay in speech because of his repeating. should I just drop it? How should I handle my sister? Did I make a mistake? Please help.