We can't really tell you how to get drugs
Vyvanse is a legitimate medicine for some people. By asking us how to score drugs for you, you're making it harder for people that really need it to get it.
Vyvanse is a Schedule II substance, which means it's potentially highly addicting for those that abuse it.
If you go into your appointment without attempting to scam your doctor, and proceed to tell them exactly what symptoms you're having, they can help you. If you don't, you're in for a roller-coaster ride which either ends in you spending months and years of hard work to get over drug abuse, or you succumbing to drug abuse--letting it rule your life.