I completely agree with you and others that your discipline for the notepads was just fine. You know your daughter best. Keep that in mind thru everything.
When my son was in 3rd grade, he had a teacher I asked for - our school will take a parent's wishes into consideration when placing children in classrooms. My oldest child had this teacher and she was great. For months my son would tell me she was mean and didn't like her. I would get reports from her telling me how awful he behaved. Knowing my son is a handful (so like his mother), I told him to cut it out and behave right.
In March of that year, the teacher sent a letter stating she was requesting an evaluation of my son for ADD/ADHD. I ignored it as my son had been tested (my daughter was being tested so I figured he might as well be, too, and by an outside independent psychologist) twice before and he did not have ADD/ADHD at all.
A month later, I get a phone call from this teacher. She's demanding I have the testing done or ELSE. She starts to beraid me and informing me she will take the necessary steps to do what she wants. I replied "fine, do what you think you need to." After I hung up the phone with her, I called the school and asked to speak with the school's psychologist. As I knew him from dealing with my daughter, I spoke plainly but civil. I am the mother and I do not give permission for them to test my son since he has already been tested and there's nothing wrong. I also informed him that if they or she pursues this any longer that I would take some necessary steps of my own.
I then sat down with my son and had a long conversation with him bout his and his teacher's behaviors. My point of the conversation was this; do the best you can to get thru the rest of the school year as I can't do anything this late in the year. I told him he did not have to like his teacher but he needed to be civil and do his best.
I hated having to tell my son he had to suffer with this teacher. I waited til the end of the school year before contacting the principal for fear of retrobusion for my son. It took 3 years and a year of homeschooling to bring the joy of learning back to my son.
As parents, we want to believe that every teacher on this earth is a kind-hearted soul but the fact is some are not. Get more involved with your daughter's classroom. I know you said you work during school hours but maybe your boss will let you come in early/leave late so as to have an extra long lunch hour once a week to volunteer in the classroom? Talk with the other students' parents, maybe at PTA meetings, and see if you hear any similar issues for their children. It may only be that your daughter has found this teacher's "buttons" and we know how kids are with those! But then again it may be this teacher and her problems communicating properly with the students.
The more involved we are as parents' in our children's education; the better adults they will become!