I've not read the whole thread yet, but think I'm in a fairly similar situation to you, OP. I'm mid thirties and know time is running out for me.
When I was much younger, I had a miscarriage and was relieved I didn't have to make any decisions myself. I'd just started uni and had no intention ever of having children. I've gradually changed my view, probably over the last 5 years, but life has got in the way. The men I've been with, I couldn't imagine settling down and having children with them, we had fun but they weren't the settling down type. Work things have got in the way, uni courses etc.
I regret not doing this sooner. I regret prioritising work and study. I love my job but if I didn't pick up the extra projects, take on extra responsibilities, someone would still do it and no one would suffer as a result.
Now, I think I'm in the right place, work-wise and financially to actually start trying. And I was considering it on my own. But I've just started dating a lovely man and I'm stuck again, not knowing whether I can leave it a couple of years til I get to know him better, not even knowing if he wants kids, or whether I put my need for a baby first.
I know if I never have kids, or at the very least try to have kids, I will regret it forever.