I switched from Adderall to Vyvanse 70 mg about 4 months ago for my ADHD and I love it. I haven't had any negative side effects and I feel like myself but I can finally concentrate and have the motivation to do things that used to be such a hassle. How do I know if my dosage is right or too much? I feel normal but on occasion feel jittery and some days I feel my heart beating kinda fast. I don't drink caffeine when I'm on it. Is it normal to feel your heart beat at a someone fast pace every now and then, when sitting down and not exercising? Otherwise I'm thinking about trying my brother's 50 mg vyvanse tomorrow to see how that feels. help please?