Best of luck to you and your family. My advise is IF your child needs medication, don't be afraid to try it but don't be closed to stopping it either.
In my experience, I have found that IF a child truly has ADHD then the proper medication works wonders. For a child that is misdiagnosed, it can cause more problem than it solves.
My son was always a busy body and seemed hyperactive. Based on the questionaires and behavior, he was diagnosed as ADHD when he was 5 or 6. He started medication, against my husband's wishes, and he bagan to cry EVERY night for two or three hours and didn't know why. He no longer participated in the classroom...seemed sort of "out of it". I secretly took him off the medication...no one but he and I knew. A few weeks later, his daycare provider and teacher told me how well behaved he had been and how much better everything was. Imagine their surprise when I shared that he had been off the medication for weeks!
My niece on the other hand, is a classic case of medication working. She does better (not great) in school and her behavior is MUCH improved using the right medication (I forget which one they have settled on but there was some trial and error).
The one thing we have found is that the medication is sometimes used as a crutch or excuse. She may push her luck a bit and then say "well, I forgot my medicine today". If a dose is missed and others (like her brother) knows it, they tend to provoke her and then blame her lack of medication. I had both them and my own one day and she hadn't taken her medication. When they told me, I said "It is only one missed dose so you are still going to behave for Aunt L. today, right?" She agreed and was doing very well. Later the boys were provoking her and making her holler in the car while we were going down the road. I informed them that if they caused it again, THEY (not her) would be the ones in trouble. They stopped and so did she.
Her mother and my other sister were shocked that she behaved so well with not having her medication. That is where I believe that your expectations can make a difference for the child that needs medication but occasionally misses a dose.