I think every daughter has a different relationship with their mum. Not normal but what works for them.
My relationship with my mum is different to my sisters relationship. We are both close but my mum definitely relies on me more for support etc.
I am the youngest by about 9 years. My sister was a different stage in her life so I assume I was just there more.
I see my mum about 5 times a week, sometimes more. We are great friends, we socialise together. Days out, nights out, dinners & games night. I think my mum tells me everything, probably some things she shouldn’t share with her daughter like issue ms with my dad, nothing bad just normal married life. Whereas I will hold some stuff back as I don’t want worry her.
I have been in a bad place the last 6ish months due to a close friend passing away suddenly but as she has been going through some issues I haven’t raised it as I know it would worry her more and add to her anxiety that I’m not ok.
My sister prob sees her once or twice a week but messages daily. They rarely do anything “social” unless I’m involved and arranged it.
I think you need to decide a relationship that you are happy with. She sounds like she leans on you a lot for emotional support and you don’t really get that back from her? Do you have others in your life to talk to and get your support from?