rose, I am sorry you have had this shock.
and i am sorry oyu feel got at here.
but please listen to the nursery. they may not have handled things in the best way, but htat does not mean you should throw the baby out with the bath water.
out of your list as to why you thik your ds is not autitstic - all but one apply to my dd1, who is severely autistic.
she has a speech delay (actually, she has a language disorder - the speech she has is very advanced, btu there are huge gaps in the development, so there are also some very basic speech things she cannot do).
it can be a massive shock to hear that osmeone thinks there is osmething not "normal" about your child. I still bridle every time something unusual is mentioned ot me about dd1 - and she was dx'd 4 years ago... it is the mother instinct - my need ot defend her all the time.
please, please just listen to the nursery. don't do what you are accusing them of, and jump to the conclusion that, because your ds seems fine within the confines of his family, then he is fine. put in for the assessment- it will take months to come about, and if by then you have been proven right, then cancel.
you will not end up with your ds haivng a label he doesn't deserve - it doesn't work like that. but oyu might end up with a means to gettign your ds the support he may need.