To me, you sound like a mom who is frustrated because you have a daughter, who is entering the pre-teen world and is testing boundaries.
I have a son who is 10 and we have been going through a lot of the same things. I empathize with you!
For other reasons, personal, we have had our son going to a therapist for several years now and, as he has entered this phase, we have been able to receive some really great guidance from him. And, I can assure you, there have been many times that I have gone to him practically pulling my hair out.
1. This is the age where they want the positives of being more grown up, but do not want the responsibilities that come with it.
2. They are figuring out where and how to push the boundaries. To see what will happen when they do 'x' or 'y'. To try and exert independence and, in some instances, it is misguided.
The biggest thing that we have learned is consistency. It doesn't matter how big or small the issue is, always be consistent. If your daughter is told to do something and chooses not to, she has made a choice and in making that choice she has also chosen a consequence. She is old enough to understand this and discussing this with her is an excellent way for her to not only know the full process, but feel "empowered" by making her own decisions. With every decision comes a consequence and it is up to her whether the consequence is something that will agree with her or not. It is up to you to be consistent, every single time.
Another big thing is this; "acknowledge the feelings, address the actions" This is HUGELY helpful. Everyone has feelings and everyone needs to have those validated. Sometimes those feelings, however, can lead us to do things that aren't right, if we don't think about it beforehand.
For instance: my son was upset about having to wear a belt. He lashed out and threw a fit. So, I sat down with him; why was he so upset about wearing a belt? - I found out, because he had been made fun of. I acknowledged that feeling, that it was hard and not fair and not right. HOWEVER, the action (the fit) was not the right way to express it. Or when he gets frustrated at his little sister. Little siblings can be SO frustrating, acknowledge the feeling, however, it is not ok to yell at her - how can he react better to the frustration?
Consistency, acknowledge the feelings and address the reaction. Take the emotions out of the equation. At a time, entering puberty, that emotions are ALL out of whack, they need for us to be the solid ones. There have been plenty of times that I have needed to put myself in a "time out" to gather myself, so that I can address things appropriately.
Hang in there!! It is good that you are so concerned about your daughter - you are obviously in tune to her :o)