Well, you're in a different situation than when your daughter was a little girl. She is legally an adult now and legally makes her own decisions. From now on, if she comes to you, it's for advice, not rules. (Unless she still lives in your home - then you're also a landlord and you have to set rules.)
I don't know if your daughter is making the right decisions. If she isn't, that's one problem (hers - and *she* is responsible for all her decisions). Your being unable to be a leader in your family has been another problem (yours). Now you have to tackle not so much what your daughter thinks of you as what you think of yourself. In a way, you can't put your foot down about whatever you need to put your foot down about until your spine is strong enough to make your foot move! But I wonder if this is something you can do by yourself. I tend to think that wise counseling can be a good thing, and if you can find some, you may learn some things about yourself that you will be glad to know.
I have found, sometimes by sad experience, that what children of any age say they want isn't always what they really want. A junior high child, for instance, may say, "I just wish my parents would leave me alone!" when they mean, "Now matter how interesting the world is, I just wish my parents would love me and protect me because I'm pretty afraid of growing up and having to be responsible." Not that they'd ever, ever say THAT out loud! I remember a friend of my daughter's who was about to quit high school just before graduation. She was intelligent and in many ways mature, but she was simply afraid to think of herself as more than a kid. (She stayed in school and came out all right.) Sometimes adult children make decisions they know their parents won't approve of - and go to the same parents seeking approval! What's wrong with that picture? Could they be really saying, "I am not quite confident of myself - can you think of a way to help me out and guide me in the right direction?" (Not that they'll ever, ever say THAT out loud, either.)
Hope this helps a little.
(P.S. Just read your "so what happened" post. I understand your situation a little better. You need not only to do what I suggested above, but also to treat your daughter as the adult she is. At this point, that's LOVE! Adults who share a house share the work responsibilities. If she, as an adult, doesn't want to do her part of the work, she has two choices: 1) she can hire someone else to do it for her, or 2) she can find another place to live. Is she going to be paying part of her own college expenses? Perhaps she needs to do a bit of that, at least.
But her dad is going to have to deal with her in these matters, since right now you can't. Your job may be standing aside, letting him do it, *not* "protecting" your daughter, and - when she complains - saying, "What your dad says goes. He is right." Expect some dissension. It doesn't make you a bad mother if your daughter gets mad at what you do. You have more experience at being a grown-up than she has, and it's your house. Separate your problems from her problems.
When I was a young adult (long, LONG ago) my parents did a lot for me. And I didn't mind a bit. My dad had many struggles putting himself through school and was determined to provide for his family - including his children's educations. So I never had to do any supporting of myself, and I never had to get a job except for the experience (and I was allowed to keep all the money). Even after I graduated and was living on my own for a year he still sent me a moderate allowance to supplement my entry-level salary! I understand where my father was coming from and appreciate it, but I think I would have been better off learning more real responsibility, and learning how to handle money as an adult must handle it. I would have known they loved me just as much. No parents do things perfectly - they just have to try to do the best they know how.)