Yes. She's not being adult at all, and she's stopped being a mom. Looks as if you have turned into HER mother....I'm finding that I have to do this with my parents now, too, but they are getting on in years. I don't have to like it, however.
The only thing I can tell you is the same as kaliope...don't expect anything and you won't be resentful.
She isn't likely to change so I would mentally form a new relationship with her....less mother/daughter and more annoying friend/friend.
You can TRY to have a heart to heart, but my bet is that she'll have a tantrum.