med dosing | ADHD Information

I have a strange question.  I take 60mg of adderall a day.  not the time released, it didnt work very well for me.  I find that if I dont take it I am not a very nice person to be around.  I am just a plain bitch.  I take my med 3x a day in 20mg dosages and I find that by between 4-6 pm I am feeling tired and spacing out a bit.   I go to college 2x a week at nights and I work nights so this isnt good.  My job requires me to be alert and able to pay attention to detail.  Ive found myself taking an extra dose to get me through the rest of the night.  It works and I am able to get to bed not long after I get home.  I don't require the extra dose every day, just days when I am working more hours than normal.  Its only Wednesday, Thursday, and Friday.  Is it possible to have extra pills added to my prescription by my doctor to get me through these days so I don't run short for the month, or is that the max he can write for me without seeing a psychiatrist.  I am in counselling, but it's through college.  Thanks