Normal for 2.7 or should I be worried?

[LaTristesse]

DS is 2.7 and I find his behaviour so hard to deal with. When we're put with other children he will always be the one to push, shove, poke, shout, slap, pull faces, basically make the others cry. He doesn't bite or pinch and most of the above is done with a weird twisty face on like he's trying to hold back but just can't. I'm at the point where I'd rather just do stuff in our own.

He refuses to listen if I tell him that's not what we do, I get down to his level and repeat ad infinitum but still he does it.

DH also gets this treatment, yelling in his face if DH comes anywhere near him. DH isn't allowed to bath him, kiss him goodbye in the morning, talk to him, nothing. It has to be mummy. But mummy is tied up with 7mo sister and fast losing the will to go on.

Does this sound normal and will it settle eventually? Or do I have to be worried about ASD etc? I'm terrified he'll be the class bully or a psychopath when he's older! He's starting preschool in a couple of months and while I can't wait to have a break for a few hours a week (and j feel guilty about that), I'm dreading them not being able to cope with him.

I've been trying to follow positive discipline with him, so no punishments etc, but that's not appearing to work at this age!

Maybe he is doing this to get attention? You mention a younger sibling, could it be a bit of jealousy and misbehaving might bring the attention, the younger one has taken away from him?
I have a 2.2 yo and we experience a number of tantrums, bites and defiant behaviour on a regular basis. We deal with it very firmly, explain was the behaviour is unacceptable, use the naughty corner but never shout or hit/slap him. In short, we praise good behaviour but reprimand and punish poor one.
I think there comes a point where "positive" discipline is a bit of a myth. By definition, IMO, discipline is not a totally "painless" process. Your DC will challenge the discipline you are trying to get him to adopt and at one point, I think it's fair to say him: "well if you don't like it it's tough". And you can do this without being confrontational or aggressive, just firm and determined.
He does not want Daddy to give him a bath? Neither does mine mostly. But that's tough, daddy will give him a bath anyway. He is yelling, told to stop, but yells again? Naughty corner and told why he is there.
It is a work in progress, we have good days and bad days. DS knows where he stands with us and is getting better at following instructions. At nursery, he is well behaved (he sometimes bites, but it's becoming rarer fingers crossed).
I'd add that in the case of mine, his language is not very developed yet and I think some of the frustration he shows comes from there.
So no, your DS doesn't sound unusual to me.
I hope I was not patronising, I sound this way, I apologise it was not the intention.
Good luck.

DOn't want to post and run but am at work so can't do a long one but...re: worries of pre-school not being able to cope, my ds1 was and still can be quite a handful in many of the ways you describe. Funnily enough, pre-school has worked wonders on him and he seems to behave pretty impeccably there. You might be surprised.