Beware "experts", they don't know everything, you should also think for yourself.
My son is now 16, at 3 he was diagnosed PDDNOS (Pervasive Development Disorder Not Otherwise Specified, first rung on the ladder of autism, but a symptomatic "syndrome"), they said he would need a full time care/assistant with him in primary school. I laughed out loud, I thought they were joking.
It came about because the district nurse said at age 3.25 (roughly) he only had 12 words. I couldn't believe it, but then I looked closely and maybe 12 was right, but he had no problems communicating.
It wasn't helped at the time by the mother wanting to play the "I am too sick to work, but not too sick to look after the children" game, and she was encouraging any/all possible diagnosis.
School couldn't get funding, he went anyway, there was no problems.
Fast forward he is 16 now, one year to go in high school, top 5% of studends easy, 1% in some subjects, works part time at local engineering consultants, plays multiple musical instruments, taught himself piano to surprising degree, as well as maybe a dozen computer languages, via youtube and kahn academy. A little unusual, but a lovely child.
His sister is 13, for other unrelated reasons recently ended up at the child psych and left with a formal diagnosis of autism. She is the most normal person in the house, yet the only one with a definite diagnosis. She is similar academic status to her brother.
I hate what to think what might have happened if they had both been labelled at a young age, it can be a self fulfilling prophecy.
I am by no means saying everyone just ignore the drs and go your own way, but you spend a lot more time with your child than any medical professional, take what they say and apply common sense and question everything - you have to be careful there are whole industries set up around wanting to diagnose your child, more help isn't always better, but often a little help is.
I grew up in NZ, I live in Australia, when I grew up strange children were just, a little strange. Life went on. These days the "normal" pigeon hole is very narrow and if you don't fit in it is like alarm bells immediately go off everywhere. What might be less than a years difference in developement in one narrow area all of a sudden becomes a big problem.
I wonder if in todays world if someone brilliant like Dirac would not have got shunted off to some institution and never heard from.