13 mths between them, unbelievably hard for the first year as DS was, in effect, barely out of babyhood when DD came along. Though luckily he walked just around the time she came along and was effectively forced to master using his own spoon and eat lots of finger food almost immediately after her birth if he wanted to be fed!!!
However, now, utterly and absolutely brilliant, they've never known life without each other and are best friends and do everything together despite being opposite sexes.
I would not have it any other way and would do the same again given another chance. We didn't go for a third for all sorts of reasons, though, a part of me was that I would only really want a third a year later again, max 2 years later and I simply did not have it in me at the time. I had a large gap between me and my sister and it's been nothing but trouble for nearly 4 decades so I would never wish a large gap between my own children.
GO FOR IT (unless you already have?!)