Thank you for sharing, this has been a different perspective to most poster's on here so I really appreciate hearing this insight
That's because I'm from a working class background, and Mumsnet I think is a more of a middle-class space (or so I keep hearing).
I currently live in a rural area in the U.K, and for the last few years, have had a fairly decent but but unreliable job. The upside is that my income has been a bit higher than most people here who are on low wages and get by on seasonal work. Yet, as a single person, despite my big deposit, I can only afford the very bottom of the housing market, (and those houses are shit holes that required thousands upon thousands of pounds to renovate). That's not child related, but it could be what you'll face too if you don't have a partner.
However, for over a decade I've also lived and worked in some of the U.K's largest and prominent cities, so I have perspectives on both worlds. Some of the social aspects of what I've talked about is worse in the countryside. Like here, women seem to move absolutely everywhere that's social pairs or groups. Like they'll walk their dog alone or go shopping alone, but otherwise everyone here is always with someone. There are a few times I've been started at a little for going into a coffee shop by myself. It's not hostility, but I think going alone is viewed as quite embarrassing or social faux-pas. Certain things apply to the city too, such as the fact that statistically, you will be in a minority if you don't have children by the time you're 35, and that can still be alienating. That's not a case to have children, because mothers can suffer from a different type of loneliness and politics at the school gate, but I'm just showing what life can be like otherwise.
When I was younger, there was a period where I thought it was mainly due to my personality, interests, or lack of maternal feelings in comparison to other women (but I don't dislike children), but then I realised that other things, such as how I felt my relationship had such a bit influence on those feelings as well. There are other important factors, but I don't want to elaborate more on it than that because it's too outing.
I don't know if this is a reasonable fear or if I'm being disproportionately driven by childhood trauma
That's not an unreasonable fear. I think the main women who have found single motherhood ok, are those who had a very good income, were reasonably healthy, and had family networks close-by to give them a hand. For anyone else, it's very rough.