Everything is temporary. My life was a blur and my head was spinning the first 6-7 months but now things are much better. The lack of sleep is way worse the second time around because you have a toddler running around from the start of morning until bedtime...you can't sleep when newborn sleeps...and Somedays there are no breaks (as soon as one wakes up the next one goes to sleep).
BUT this is all temporary. Now both my kids STTN and nap at the same time for 2.5 hours, they play together and independently and it is much easier than 1 year ago.
I don't know if there is "perfect spacing." Most of my friends are having kids now and I personally think it is worse. They have a 2.5-3 year old acting out, getting jealous, refusing to nap, running around the house, "trying to help" with baby (picking up the newborn from bouncy), and the mothers look like a mess all the time.
DS was not planned and it was hard but DD was young, pregnancy was easy (she napped 2x a day, wasn't walking), she didn't really understand or really care about the new baby and played very well independently never showing jealousy (until he got mobile and could take her stuff), and if I went out she was still young enough to strap in a stroller.