15 months between DD1 and DS and then 2.5 years between DS and DD2.
3 children in under 4 years was bloody hard work and still is sometimes but they all get on well and there is a lot of love between them all.
I find the dynamics change regularly between them all. DD1 and DS are very close and have strong bond but they can also over do it and need time apart. DD1 and DD2 get on well and DD1 can be very nurturing towards DD2. DS and DD2 also get on well and have a very loving relationship.
They can also fight like cat and dog of over tired or over stimulated, which is easily done with close age gaps.