We're not LTTTC, we did start TTC beginning of last year however we are a same-sex couple so our circumstances are our own doing. That said, we did hope when we first had DD of an age gap of 2-3 years. I never wanted an age gap of more than 3 years, but finances and work circumstances pushed it back, and I had to be ok with possibley 3 years, maybe 3.5, and then when pregnancy didn't happen last year I then had to be ok with a 4 year age gap. DD will be 4 years 3 months when this little one is born in a few weeks. At first I was disappointed. I came from a big family, my sister and I were 18 months apart and I liked that, we always had someone to play with (and fight with LOL). I was so angry with myself that DD had missed out on that closeness and having to be alone in her early childhood, play by herself, not have someone to share and giggle and whisper with. I am slowly becoming ok with it although still very sad for her, she is a wonderful age to be a big sister and is very sypathetic to when I need to rest and has helped pick out a lot of things for her little sister, so while I am sad it didn't happen 2 years ago and that she doesn't have a small age gap, she is hitting her 'perfect age' in relation to being a big sister. (I'm just hoping she can grow out of her 4yo tantums and attitude in the next few weeks LOL!).
I did struggle with the thought that another one might not happen, but again that was mostly circumstance. I was worried that we might never be able to afford more cycles, and then while we had some issues conceiving last year, they were fairly normal and related to time (and some PCOS and hormone issues) which is fairly minor in comparison to most.