Toddler developments

[Akshayan]

Hi
I am a first time mum and is wondering if anyone could advise me on my childs behaviour. My son is 21 months old.
He speaks about 40 words but hasnt started sentences yet as in putting two words together. The other bit I find very strange is that he is so obsessed with water like he would love to play with the sink, tap open all day, wants a cup to pour the water in and out. If we remove him from the bathroom he gets very upset. Recently he has started to treat building blocks like cars and just glides them back and forth instead of stacking them. I've tried to show him to stack and build and demonstrated it myself but he has no much interest. I was just wondering whether this is normal behaviour ? He seems to like cars a lot in recent few weeks and keeps rolling them back and forth and sometimes would move them slowly in slow motion and watch it closely by bending down to the cars level. As a first time mother, I am finding these behaviours strange like is this how they would play ?

I think his speech might be on target, I think they should have around 50 words by 24 months?

As for how he plays, has anyone suggested doing the MChat Test to are if he's at risk of having ASD?

I'm a nanny with many years of experience of toddlers and this sounds totally normal!
With the water thing, it sounds like he's working on a schema - I will try and find something online that explains it in a simple way and post it. I would give him lots of opportunities for water play and also other pouring/filling/transferring activities such as sand, dry rice, beans, chickpeas.
With the blocks and cars thing - he's playing with them in a way that makes sense to him at the moment, it might not be the way that adults think they "should" be played with but it's still valuable play. In a a couple of months he will probably change how he plays with them.

schematic play explanation

Also a nanny with many years experience and totally agree with pp.

It's completely normal.

Using a block as a car is no different to using a stick as a magic wand. He's using his imagination.

First time I have come across this test. ASD is always on my mind as my cousin is on the extreme end of ASD. So I always try to pay a lot of attention to his behaviours and how he plays. Sometimes it does drive you crazy because a lot of the symptoms are present in normal children too. I just did the question and the score came out to be 1 which is very low. Thank you so much :)

Thank you to all for your advise. I will give him a lot of schematic play opportunities. He will be soon having his 2 year checkup. He goes to a nursery at the moment so they will track his developement too :)

Sometimes its so reassuring to hear things from someone who has had so much experience with children especially when you are first time mum where you dont know what is normal and what isnt. Thank you so much ❤