We had our first three pretty close together, then we were undecided for ages about a 4th, so there is a larger gap between DD2 and DS2 - she was 3yr 3mths when he was born. It was pretty full on for a little while, because I had one child in preschool, one child at school and one at home still, so when he was born he just got dragged from pillar to post at times LOL, but it was fine. He was pretty cruisy for the first few months and by the time his reflux started causing problems we were already well adjusted to life with 4. I don't think you get busier the more kids you have, I think once you have kids you are busy period. If you only had two I reckon you'd be doing just as many activities as you would be with 4 kids. I reckon you should go for it!