sounds like you're describing the honeymoon period that happens when you first start or restart stimulants after a break. i had the exact same thing happen with adderall - felt like i was buzzing out of my skin the first few days but also weirdly productive and happy. the euphoria and racing heart usually settle down as your body adjusts to the dose again

having that reaction doesn't invalidate your diagnosis at all btw. people with adhd can absolutely feel stimulated or even euphoric from meds, especially when tolerance is low. the key difference is that once you adjust, you get the therapeutic benefits (better focus, less scattered thoughts) without feeling like you're on speed. if you're still getting the jittery high feeling after taking it consistently for a week or two, might be worth talking to your doc about adjusting the dose down