22 month gap here.
First year of #2 was a FUCKING BLUR. It was just work work work work.
I didn't mind having 2 in nappies for a good year, I was quick at nappies. I didn't have any problems with feeling I wasn't giving #1 attention - he watched a shit load of cbeebies between 2 - 3 but who cares? That didn't stay the same long term. As long as he was in the room with me whilst I was BFing I didn't care. I was sensible that it wouldn't scar him for life! He loved it!
But the relentlessness of one of them always needing something was a shock. With one, when they're quiet, all is quiet.
With 2, when one is quiet, the other is kicking off! So it is twice the demand.
The house was a mess and we ate shite. Both were bone crushingly bad sleepers. I didn't sleep for 4.5 years in total. I just survived.
BUT!
Once they turned 4 & 2 (ok, 2.5 when they slept through) everything got a lot better.
Now they are 5.5 and 3.5. And are very close. Have been invaluable to each other during quarantine. Are at the same level to enjoy the same cartoons and the same dinosaurs etc. Laugh at the same stuff. Both like crayons and painting on plates. Both have bikes with stabilisers. Both parrot the same stupid sayings over and over and fall about cackling at each other.
I know it's not going to be always this nice. Next door has a boy of 16 and a girl of 14 and they just grunt at each other and piss each other off and blank each other. Their parents are sad. But it may swing the other way when they grow up.
I'm v v v glad i got everything out of the way in one go. There's a lot to be said for just spending a few years pulling the plaster off in one go!