My son is a bit younger - will be 4 in July - and I think his nursery think he is on the autistic spectrum. I think he's shy. But he's always been a bit on the later side of hitting milestones and we are in the process of being referred. His speech at 2 wasn't that good at all but then almost overnight, it just seemed come on so much. He does speak quite well now, although definitely not as good as a lot of kids his age.
We had a nightmare with his potty training. He hates change so it was a nightmare to start but then he was ok. The pooing was never ok. Very, very hit and miss and more miss I'd say. I used to send him to nursery in pull-ups to be honest as I just didn't want them to have to be changing him if he was having accidents as he's only there 2.5 hours a day and all the other kids are toilet trained.
The breakthrough for us - not telling you have to have another child to do this though ha! - was potty training our 2 year old. I don't know if it was to do with this or if it just clicked, but he literally hasn't had an accident for maybe 2 months now and he was having accidents pretty much at least once a day.
I remember posting on here about our issues with the potty training and people telling me that maybe he wasn't ready and to put him back in nappies but - aside from the 2 hours when he was at nursery in a pull-up - I just couldn't undo all the work I'd put in to get him dry. He's very much a child of habit. He doesn't like change so I knew if I stuck him back in nappies, he would have gone back to not being dry at all.