You didn't say how long he had been taking his meds. typically doctors start off at the lowest levels and wait for parental feedback to know how the medication is working. So its recommended that you inform your doctor what is going on.
Couple of other thougts. Has anything changed in his daily routine. How is school going. The stress of that can really hit a child as they are coming off the meds. Is homework getting to him? Also the not sleeping can really contribute to his anger. Kids need their sleep. Is the lack of sleep due to meds, his ADHD, or some underlying physical condition? And that leads to the last question. What kind of a doctor is he seeing?