My background is fairly similar. DM of similar age, but still living at home. Had to RTW when I was about 3wks. D(G)F was made redundant around that time and D(G)M was a SAHM for young members of the family and in a caring role for a family member with SN. Every penny counted as a large family was being kept on limited benefits and a very low salary. It was still an era when being a young, unmarried mother was deeply frowned upon although my parentage was always open. I could plausibly have been passed off as the youngest sibling.
DM was ready to move on when I was a pre-schooler. For practical reasons, it made sense for me to stay in the family home rather than being there for childcare and sleeping somewhere else. DM was a bit like a EOW type Disney Dad. She was there, but mainly for nice bits, not the everyday parenting.
I was loved. By DM in her own unorthodox way, but more critically by my D(G)Ps who I naturally called my parents. It was a secure, loving family, just not the usual 2.4 children of that era.
My adult relationship with DM is not easy. Not because of my background on my part. I've always accepted that she did what she could with what she knew at the time, and I was happy with the package of love I had. She does have baggage about it which has flared up most around stages like me going to uni and getting married. I think it hit her hard that I was a grown-up and there was no going back to reclaim her little girl. She also has baggage about other issues which connect to D(G)M which can be quite messy to deal with.
What we have in common is that awkward circumstances lead to our unusual relationships, not personality. Personality may be an added complication further down the line, but it isn't the cause, and personality can be a difficulty in the most average of circumstances.
I do feel that DM misses bits of me and my development, sometimes her need to express her motherhood is just out of touch where I'm at in life, I didn't need mothering in my 20s, I needed her friendship by then, and I think she's struggled to understand my independence of thought and tends to blame D(G)M or DH.
D(G)M is alive and still the main mother figure to me emotionally. I lost D(G)F in childhood which affected the family dynamic. Who knows what the future holds and how it would hinder or help family dynamics.