Partly.
I had my first at 33 and then had another baby a few weeks ago - I'm 35. It's early days but I think we are stopping at two, for various reasons. My DH has only ever wanted two, and also both of our mums help a lot with the two we do have - they're early 60s now, but obviously not getting younger and it would be harder without their help.
When I was 15 or so I was diagnosed with PCOS and told I wouldn't get pregnant without medical interventions, and that coloured my attitude towards pregnancy and parenthood. I didn't want to go through IVF, so I just assumed it might not happen and focused on building my career and having a lot of fun in my 20s.
Turns out I fell pregnant spontaneously after coming off the pill without too much bother, had DC1 and then fell pregnant again very quickly after finishing breastfeeding. Both times, I had straightforward pregnancies, easy births and healthy DC, and also found breastfeeding came easily.
I really love being a mum. Part of me thinks if I'd known what my body could do as a teenager I'd have started earlier and had 4 or more. But, my lovely DH wouldn't have been up for that so it would have been a very different life. And I did make the most of my 20s and maybe I'd have regretted missing out on work and partying and travelling if I'd had kids then.
Or maybe I'm just emotional as DC2 is growing out of his newborn clothes and I can't imagine not putting them away for another time!