I would talk with my friend and let her know that I was hurt, etc. Wait until you can do this calmly. Word your sentences using "I" statements so that you are letting her know how you feel and not accusing her of anything. "I am hurt by the way you said that my daughter may be autistic." sort of statement. Once the two of you have handled your hurt feelings ask her what she sees that has caused her this concern. Keep in mind that you are communicating with her and not venting.
From the description of your daughter I would think that she's normal in her development. I am glad that you've done this much research. I also want to tell you a little about my experience with my grandson so that you can use this free resource.
My grandson was still not talking clearly and still using just a few single words when he was nearly 3. His pediatrician suggested that his mother have him evaluated and gave her the phone numbers of a private professional as well at one for Multnomah County Intermediate School District Office. We learned that each county is mandated by law to evaluate and provide services to any baby/child who would have difficulty succeeding in school. IF the child is evaluated and found to benefit from services there are more intensive services available before the child is 3. It turned out that my grandson has speech apraxia and has been in speech therapy provided by the school district since he was evaluated.
One of my friends first suggested the possibility that my grandson was autistic. She worked in the school district providing services for autistic children. I dismissed her suggestion. I did feel some concern but I believed that he was not autistic and accepted her comments as showing her concern for me and my grandson. She didn't try to convince; just made the suggestion allowing me to ask her questions which I did.
It also turns out that he has learning disabilities most likely related to some degree of autism although he does not have classic symptoms. I was glad that my friend had made the suggestion that his was possible a couple of years before I became aware that autism was a part of his difficulties. Her suggestion gave me time to process the idea and to do research.
We think my grandson is also quite smart. As he became older I realized that he does quickly learn and knows as much as a kid his age but he isn't able to put what he knows together in a mature fashion. This is something that I couldn't see when he was younger. I think that a professional person knows how to look for signs that aren't obvious to the untrained person.
I suggest that you call the County Intermediate Education District and ask about an evaluation. They may say that your daughter does not have sensory processing issues or any form of autism. In which case you will be reassured that your own assessment is correct. And if, by chance, she does need some assistance you are getting that for her while she's the age to benefit the most from intervention. This is a win/win situation. You have nothing to lose.
When I was doing research I discovered that there are many disorders/learning disabilities and then many variation on those. I found it impossible and still do find it impossible to fully understand my grandson's difficulties. Lack of speech is obvious. He has other characteristics that are not obvious.
Two characteristics that I thought of as normal when he was two and that have become even more intense is his seeking strong touch. He runs pel mel when he greets someone. I have to brace myself so that I don't fall. I have repeated over and over for 2-3 years that he should slow down etc. He still runs and nearly knocks me over. When he was a toddler he'd run hard into walls and furniture. He'd bounce off and keep on running or sit down and cry. He couldn't seem to learn how to avoid solid objects.
The other thing is that he would stuff his mouth so full that he didn't have space to chew. He still does that too.
A sensory disorder can manifest itself either has needing strong touch in order to feel something or the opposite being sensitive to light touch.
Both of my grandchildren are strong willed and independant. As toddlers they had frequent temper tantrums. My granddaughter outgrew the tantrums. My grandson at 6 still has frequent tantrums. He has difficulty following directions. He can, when he chooses to, do one thing but we can't tell him to do 2 or 3 things at the same time. At 2 this was normal. At 6 it isn't.
On his own my grandson counts. He can start at 18 or go up in chronological order as well as starting at 1 but if you ask him to count to 10 he gives you a blank look. Same for the alphabet. He knows his numbers and the alphabet but he has difficulty using them.
My grandson is a delightful child. He is liked by adults and children. He is very social and fun to play with. He does have difficulty knowing how to interrelate at times. I'd guess his social skills are more at a 3 yo level. He's not a follower or a leader. He's often in his own world but not the silent withdrawn world that I'd associated with autism. He's active and searches out people with whom to interact.
I'm saying that recognizing autism, sensory processing disorders or any of the numerous ways of being in this world that handicap a child once they're in school is very complex. Have your daughter evaluated and set your mind at ease. You have nothing to lose and everything to gain.
I just read a comment about mercury. Mercury is no longer used in children's vaccinations. You can call the health department or your pediatrician to confirm that.