I definitley believe an age gap of 3 years is optimal. If you have had 'troubles' with young Max, (I had the same with DS) it would be easier for you all in the long run.
It's hard being preggers and chasing a toddler. Unless your eldest is a good sleeper during the day (so you can have a nap too) it can do you head in.
Between 18-24 months you can get quite long periods of intense frustration and insane tanties because they don't have enough words to express themselves.
Recovery is a little harder as you can't always just doze back to sleep when baby does after a feed, when you get all drowsy when you bf. Seriously, that used to kill me as bfing made me very, very drowsy!

Its so individual, but I think you can make it easier on yourself if you hold off a few extra months.

JMHO xoxoxoxo