Okay I am totally frustrated and confused!!!

My DD who is 9 (10 in Nov) has been off her meds (Focalin XR) for the summer. School started back up on Monday. I gave her meds on monday, tuesday and wednesday, so when on yesterday morning (thursday) she said she didn't want to take her medicine because it doesn't do any good I said okay (trying it out to see if she was right) but if her teacher noticed a difference and asked if she took it that she would go to the nurse and take it immediately. Well her teacher didn't notice, but she had homework last night because she couldn't finish her work in class (everyone else did) and she was very difficult last night. How do I know if she needs her dosage upped or a different med. I made her take her med this morning but she is very adiment that she doesn't need the meds and that they don't do any good.
Does anyone have any advice or experience that might help me deal with this situation. When I talk to the dr and she always says that I am the best judge of that and to talk with the teachers, but since this is inattentive I am at a loss most of the time because the teachers look at her and don't think she needs anything or think that she is just being stubborn...
My DD does not need seem her meds when she is not trying to concentrate on school or something like that. She doesn't really have problems that we notice when at home except her lack of responsibility and immaturity.
I may be going about this all wrong. Maybe she needs the meds all the time but she hates taking medicine. I really don't know what to do because she is telling me that the medicine doesn't do any good. And the Dr. told me that she could only take them during the week and not on the weekend so I am guessing that there doesn't need to be a buildup for them to work.
I would appreciate any advice.. or presonal experiences...