Hi Storminateacup I could have written your post a few months ago, except we already live in a lovley street. Small house though. I used to lurk on this board and really struggled with the "should we/shouldn't we" issues.
I am 40, DS will be 3 in September. I have 3 siblings who I could not imagine not having. DH has 1 brother than he is not really very close to. I was 37 when I had DS. Yes, I was building a career, but we did not really want children until then (DH is 5 years younger than me). Our life was quite happily attuned to 2. I'd got to a point where I was working; sleeping; getting out in the hills a bit a week ends and starting over and thinking there must be more to life (much as I love hill walking and mountain biking). Then a small incident made DH realise that he wanted a DC. DS was born 10 months later! Very quickly our life became perfectly attuned to three.....!
When DS was approaching 2, I really began to want another DC.This despite a horrible PG with DS - hospitalised 4 times with hyperemisis and emCS, followed by a week in hospital.
I can't be sure whether in wanted another DC for DS or for me, but I didn't want him to be an only child of older parents. None of my siblings live nearby/in this country, so he has no close relationship with his cousins. I can't really explain it, other than saying to DH "I don't want to be 50 and playing football on the beach because he has no one else". I tried to imagine what I'd say when he asked why he didn't have any siblings, and could not come up with any truly satisfactory answers - all seemed to be short term or short sighted.
DH is not great about talking about his feelings, but shortly after this we had a very surreal conversation about IF we had another DC, then where would it sleep.... , which I took as agreement to TTC....then we ran out of condoms, and decided to see what happened. DC2 (a DD!) is due in OCtober. We've sold our 3 seater van, got an estate car and are preparing our life for 4.... DH is delighted! I appreciate that we are very lucky that we have conceived very quickly both times despite my advanced years, and a lady in her late 30s/early 40s could have a very different tale to tell.
So that is my story. I think what I am trying to say is that my decision to TTC a 2nd DC was based purely on instinct, and faith that the practicalities will sort themselves out.
Good luck with whatever you decide, you have all my support and sympathy that it's not easy is it?.