She is playing 'wait and see'. 
Professionals quite often smile and nod encouragingly and play that game. it's very sensible, because of course, some of the children they see are just developing at a different rate and the appointment in a few months confirms this (and they are discharged).
For some of the children, the repetitive behaviours and social issues (and hiding) increase, and so the next appointment becomes the first of many many many more on the road to diagnosis. But they will play 'wait and see' for as long as they can, because to suggest intervention of any sort costs someone money, and time, and can upset some parents.
So quite often, professionals like to have a few sessions before they raise 'label' words with parents, just to try and gauge if they are likely to freak out. (forewarned is forearmed and all that).
We are all different. Not all kids fit the same box.
Some of them have autism. The world does need to accept that autism exists.
I'm not in the UK either. I have absolutely no clue why that is relevant? ds1 had a full assessment which celebrates his diversity.
He didn't pick up an ASD dx, just 'traits', which we knew anyway. It doesn't mean they don't exist, and the paed referred him to a completely different psych for those. He's a lot older, though.
At 3.10, unless his issues are extremely obvious, an EP will always play wait and see. Unless you are in the US, where early intervention and screening is generally better, and they have better outcomes as a result.
She didn't assess anyway, did she? Didn't get you to fill in checklists etc? Just had a quick look at how he interacts at nursery?
I get that you are relieved that she didn't immediately diagnose - so he can't be that autistic or she'd have picked it up? That doesn't rule anything out though, you know that.
And she didn't say 'perfectly NT. no concerns whatsoever'. She muttered some loveliness about diversity and is coming back to observe him again.
Welcome to the rollercoaster.