I was 19 (another statistic) and one month shy of 20. I had my second at 20, a month shy of 21. So I have Irish twins, 1 year and 4 days apart, though it was tough when they were little it is great now. I just hit 30, which was my cut off for having another. There was 6 & 8.5 years between my older brother and sister and myself and honestly I didn't know either of them very well until we were adults. I did not want that for my children.
However, looking on the bright side I will be in my forties when my DS's will be out in the world and DH and I can, (as jimmiej put it), Parteeeee!!!