<human>: Provide a brief overview of the text.

I am going to the doctor's office tomorrow and am going to request he prescribe me Vyvanse. I have always had terrible troubles with my mind (focus, organization, etc) and taken various tests for ADD/ADHD which have all pointed towards it. I have seen this specific doctor prior and he gave me Bupropion to see if that may help with a mix of anxiety, depression and focus issues. It has been 4 months now and I have seen no change whatsoever. My girlfriend gave me some of her Vyvanse to try for a week because I asked her and wanted to see if it was really viable and could help me. -Her dosage is 40mg so I have been taking that once per day and have seen a vast improvement in my ability to focus on tasks I need doing and my mind seems to be more organized. I can remember the smallest details and even where I placed something 5min earlier, a task which was unheard of for me. My appetite has decreased and my sleep a tad too, but that is because I feel like for the first time I can get work done without my mind skipping every 10 seconds. When I take the 40mg it usually needs 2hrs-3hrs to kick in and the only lasts roughly another 3hrs. I was wondering if I should request a higher dosage due to my size (6' 4", 210lbs) as I've read it should only take an hour to kick in and last about 8hrs. I am also worried that by me requesting it, the doctor may think I am going to try and abuse it, as a lot of young people my age do. So I would also like to know how to request that he let me try it for a while to see if I can truly benefit, while also conveying that I am truly interested in using it for its intended purpose.
<bot>: I'm big. Visiting doctor to request Vyvanse RX. What dosage should I ask for and how should I ask without sounding like a druggy? (legitimate need)