OP I think you need to get into therapy and work out some of your own issues. to understand yourself better, your needs, your boundaries, and maybe which of them need to be reshaped or redrawn from the better.
Could also help you to see things from her perspective and understand her motivations better. maybe you have made mistakes, and understanding / owning them will be the path to a better happier relationship with her daughter.
At various points you may need to hear things from her, and accept things from her that are hard for you.
No doubt you did the best you could, with the resources available. But that still may have been hard / damaging to her.
Also she is still a very young adult. So, even if she has reflected on all of this, she is probably not yet at the point of being able to understand your choices and forgive your mistakes.
to give an example, my mum tells me she stayed in her miserable marriage for us. Implication is, it's our fault she spent 20 years with someone wrong for her. This isn't true. She stayed because she was afraid to leave, and we were a great excuse not to. But her inability to take responsibility for her own actions does impact our relationship and reduce our closeness.
I'm 40 and a parent myself. now I can see my mum did the best she could, and her mistakes and poor choices were down to her own failings. I can forgive both her past mistakes and her on going faults. I manage our relationship to be as close as is possible without it being damaging to me (which is a lot less close than my mother would like). But in my 20s I was in a very different phase, and went not quite no contact, but very low contact, while I extracated myself from our co-dependent relationship.
you'll say you didn't do what I've described, and that will be true.
But it sounds like life was hard, and she's got hurt by events.
Go to therapy and face up to yourself, your choices, the consequences. It may be that you will come to see her in a different way, you might be able to discuss it, but that may not be necessary.
Things may just change without discussion if you are working on yourself, but if you don't take responsibility for yourself and your own part in how things are, they are much less likely to.