Thank you everyone for posting such personal thoughts. It's been reassuring and informative to hear your thought processes.
In terms of my "ideal" number of children, I've never really had one. There are days where 1 feels perfect, and others where I have a longing to share my love. DH and I have talked about the possibility of adopting a special needs child, of having a small family, or having a large one, of having nondescript careers, of having a highly public life, etc. The only definite feeling I have is that I don't want a large family--say, 5 or 6 children. To me, that's too chaotic for my taste, no matter how symbiotic the relationships might be.
For me, it's not so much about achieving the right headcout as feeling that a sense of family equilibrium has been achieved--one that allows me to pay a lot of individual attention to my child(ren) and respects the child(ren)'s need for close attachment, particularly in the early years. DH and I started our family sufficiently early that, fertility willing, we could have 3 or 4 children with moderate to large gaps between them with fertility room to spare (the minimum possible gap between DS and a prospective sibling is just shy of 4 years.)
DS has been higher needs than almost any ND child I know of. He requires more, more, more of everything-- one-on-one attention for most of his waking hours, physical contact to sleep (he is almost 3 and cosleeping, though we're going to gently test his spending half the night independently), constant conversation, frequent breastfeeding, resistance to eating (he only really began eating a meal a day around 2.5) and remedies and workarounds for SPD.
DS is an extrovert par excellence. He's a delight, but an exhausting one. By the end of the day, and sometimes by mid-day, I'm wiped. By noon, I've probably heard about 10,000 words and fielded dozens of intricate questions. I would be lying if I said DH's and my relationship hasn't suffered at least a little due to DS' strong needs. DH, while supportive, has not been involved in DS' upbringing to the extent I'd have liked, and I will need more contribution to childcare from him if we expand our family. I would be strained to have a second equally intense child without more support.
If a second child were to match DS' intensity, I would need to have another year or two of interim buffer to adjust and gird myself mentally. (I say this not as an emotionally flaccid person, but rather as a tough-as-nails former consultant used to 80+ hour work weeks and dealing with travel, the media, and challenging personalities. We have been staying with my parents on vacation and they have remarked that DS' ideal adult to child ratio is 3:1 or 4:1. No joke.) DS is at an age where he is highly portable, mixes well with adults. I feel like I have some adult life back and enjoy the balance we're starting to achieve.
Where we live currently, we're surrounded by professional friends who work long hours, but we lack a family support network. (DH's family are an hour away and about as useful as a superfluous nipple.) We're contemplating a move to my hometown, for a number of quality of life reasons, one of which is a high touch relationship with my parents. We currently live in an urban loft in the heart of a cultural Mecca, which worked great when DH and I would rendezvous for a 10pm dinner at a French restaurant around the corner after I flew back from meeting clients, but it's a less than ideal environment for young children. Fantastic for raging cocktail parties, God awful for trying to keep the house quiet for an uber sensitive child to sleep. Note to all: lofts and kids don't mix!
As to reasons for having another child, I have no expectations that a sibling will be a natural companion for DS, particularly with a 4+ year spread--that would just be gravy. DH is the eldest of 5, my mother is the 4th of 6, DH's mother is the oldest of 7, etc. There is nary a friendship in the bunch, save for my Mum and her sister, who is one year younger than her.
For DH and I, it's a question of love. How much love do we have to give? Can we give another child the love, attention, and resources to optimize that child's future? I want to do my best with every child. With DS, we felt an overwhelming, burning need to have an outlet for our love. It sounds corny, but there was too much love in our life for just two people--we HAD fo share it. Enter DS. If I'm honest with myself, I need some time for DS to mature before I feel confident that I'm not robbing him of support he needs. It's possible that I might never feel that same burning again. There are some hot embers kindling now; I suppose patience is required.
For me, giftedness/intensity is a central part of this thought process.
That and we both almost died in labour, after a flawless pregnancy, so there's that.
