I have 3 and love it but I answer to your question.....
Bigger car - depending on ages car seats just will not fit
House? Bedrooms yes but what about all the STUFF!?!
Nappies again
3 kids being ill at same time and pass to parents..... just had a week of this! Toddling children are just germ spreaders!
More years juggling school, nursery, work etc unless you are sahm or have a nanny and as a sahm Mum i think it depends on the age of your older children. If both at school them I think it’s different to me.
Different holidays - I was all set to start “fun adventure ones” and now it’s back to basics - let not talk about the £££
Can’t enjoy this lovely summer sun - 12mth old won’t stay in shade, walls round garden eating stones, has learned to climb up the slide....
The fun food journey at 6months is just a hassle as it’s was good just saying ok fish fingers , pizza etc sometimes and now it’s back to thinking about what the baby needs ;-)
Mat leave #3 is just an endless School drop off / pick up or activities for others not sure when I did an actual baby thing or had a regular meet up / coffee because life just happens. I love my babies but wow certainly not mat leave #1
Older children’s toys are just dangerous! Lego, marbles etc. I am constantly assessing and on the lookout.
However I love them all so much and life is fab.
But I now totally understand why 2 is enough for some (most!)