Sorry just couldn't face putting this on the AIBU topic...
But SIL has wound me up and DH is telling me i'm being silly to get grumpy over this.
Today i took DS (4.10; asd) to a regular playgroup, only second time we went.
He enjoyed himself in his own way, not talked nor tried to interact with the other kids. Nothing too unusual there.
But again, i felt heartbroken after the session ended; having sat there through 1h30 mins of NT kids chatting and playing.
DS was the oldest there, and most of the 3 years old spoke better and interacted in a much better way than him. 
DS has come on loads in the lat year, but is still so obviously delayed.
I tried so hard not to compare him to the others but i simply couldn't not notice the things the others were doing and he can't do yet.
Anyway, back to topic. I posted on FB a bit of a sorry for myself post.
Had many comments, from other ASD mums.
One of them, commented about her DS (who has AS), and the fact that he is only learning how to pedal a bike while most youger kids can ride without stabilisers and it's yet another thing he struggles with.
I anwswered something along these lines 'i understand, and my DS is also still a longgg away from being able to ride properly too, but that's ok our dc will do things in their own time when ready'.
Come along SIL, who i quote "I wouldnt worry too much about the bike riding - J would never get on the bikes and even if we encouraged him to he would just sit there and cry. I dont think he learnt til he was about 8 or 9 old"
So i got a bee in my bonnet about her comment. Her DS J has no SN, never had delays other than... learning to ride a bike late.
Not happy, maybe i'm being too sensitive. 