Medication, brain scans, ADHD

No.13062765 ViewReplyOriginalReport
I would like to keep this short so it doesn't turn into a blog post, but to preface this, I know that some people here don't believe in ADHD, but I've been diagnosed since I was 17, past the point of "this is just a hyperactive boy" behaviour. So this was not just a psychiatrist trying to get a kid hooked on meds. I don't abuse nor take anything on a regular basis so the tolerance/brain damage explanation also falls off.
Now I am 20, and I've now heard that drugs have a different effect on people with ADHD. I've taken Ritalin in doses of 55-60mg (3 times in the past year), which from what I have read, and from what others have told me is supposed to be a recreational dose that's supposed to give you euphoria, make you hyper -- the usual upper shit. However, upon taking it, all that happened every time is that I was incredibly calm, although with a heightened heart rate, and maybe a little bit jittery, but nothing euphoric. I've heard different thing about the drug from people without ADHD, and they have said that it was euphoric while taking doses lower than mine. I could never really feel things like nicotine and caffeine either.
Now, I get that I could probably find out the answer by googling around for studies, since this is a very common phenomenon, but if I do an fMRI brain scan, (or others, I haven't looked into the different types), could I see the underlying issues and guess how and why certain drugs would affect me from the results? Do all people with ADHD experience this? If these results are visible on a brain scan, then wouldn't brain scans be more effective in diagnosing ADHD (assuming everybody with ADHD has a similar neurological disturbance), rather than relying on only patient reports of symptoms in order to develop a more effective treatment plan? Is stimulant medication really the only viable answer, considering how high of a dose I usually would have needed to go in order to feel some semblance of "normalcy" and an ability to stay still?