Hi Mrs Hairy, that sounds so like my birth family. No discussion of issues, just an expectation that with time everything would be firmly in place under the carpet and we'd carry on as normal. It didn't work. Or, I wasn't happy growing up and became very distant with my parents.
Now I'm a mother. My daughter and I were very close when she was small but the relationship fell apart when she was in her teens. Mainly my fault. Or that's how I see it. I, and her father sometimes, made some severe errors. Add that to her sibling being autistic and developing some severe difficulties at the time meant she did not get enough of the motherly support she needed as a young teen. We became more and more estranged as she grew into her twenties.
One time we were visiting my mother, her granny, together. It was a long drive together. On the way home, I broached the subject of her teenage years and said I wanted to apologise for the things I had done wrong. It led to a deep and difficult conversation where we both were honest and cried. She had some things to confess and ask forgiveness for too. Being on our own in the car helped. We had to focus on each other but didn't have to look at each other.
Now we are very very close. Not suffocatingly close. We respect each other and both are very happy if either of us gets told we have a temperament like the other. She's a mum as well now and wants me involved with her family.
I do realise this is the other way round to the story you wanted to hear, but I wanted to show you that a difficult mother/daughter relationship can be healed. With love and open conversation and above all, listening. In my case, some very hard listening. Our past has not changed but we have moved on from it.
OP, I wish you well and hope you find some way of living with the hurt of being let down by your mother. I must say that the one time I tried to bring up some difficult issues with my mother she was not at at all receptive. In retrospect, I dare say I was overly acusative, rather than approaching the subject in a less aggressive way. In fact we spent some months not talking at all. Yet we still got closer as she got older and more inform. Particularly after my father died. Now she needed me, she was a lot warmer.
Initiating a challenging discussion yourself might not be effective, but it might also be very productive. Your call as to whether or not you try it. But if you do, it would be worth opening up more diplomatically than my bull in the china shop approach.