Complex Motor Stereotypy or ASD

Everett has some quirk going on in his life.  I became concerned at about 18 months when he stopped using words he had already learned.  Right now he has a vocab of a whopping three words.  I am flattered "mom" is one of them.
In addition to his speech delay and regression there is this hand flapping he does when he is excited. Of course the combination of these two give me pause.  He is scheduled for testing at a pediatric neurologist, but in the meantime he has been having some early intervention and speech therapy.  The consensus is that everyone is perplexed by the enigma that Everett is.  He does not seem autistic due to his empathy, eye contact, affection, and socialization.  However, he's got something going funky in that little brain of his.
I over research and over think everything, so I have had many hours of concern.  It seems as if Everett enters into his own world, far far away, when he starts flapping. I can bring him back to me by calling his name or touching him.  Other adults with CMS have described this flapping as a very creative outlet which allows them to enter a space that is fascinating, engrossing and safe.  That is a relief.  Where can I sign up for this? I will go with you Ev.  Flap and fly my pollito.

he was moving his hands and mouth at 6 months...

i just thought he was jazzed about life.