Judging from your post, I actually think you might have more classical ADHD, instead of ADHD-PI - the fact that you report energy when off the drugs, is why I believe this.
Sometimes, when you have ADHD-C ( combined, you pronounced problems with both inattention and motivation) you often get a case of the sufferer not having as great of a difficulty with one or the other, and if diagnosed late in life, may be seen as mostly inattentive, when in reality, this diagnosis might not be entirely correct.
( the person with the illness may by then have found various behavioural compensations, which mask most of the hyperactivity. Especially if that was the lesser problem.)
Anyways, for pure focus, just ask your pdoc for Intuniv ( time-release guanfacin) - it has nearly no effect on motivation, but tremendous effect on attention. That's because it primarily inhibits cAMP -formation in the Pre-Frontal-Cortex.
Over-production of cAMP is theorized to be the primary pathology behind the inattention, behavioural, and emotional control -problems of ADHD. A lot of people diagnosed with comorbid bipolar-disease find themselves PERFECTLY emotionally stable on Intuniv - most likely because they don't really have bipolar at all, they just have ADHD-PH - and especially problems with emotion-control.
Intuniv is often used in concurrence with stimulants, such as amphetamines, since they compliment each other incredibly well, they more or less remove the side-effects of the other. ( they stack, heh)
Just remember to lower your stimulant-dose if you decide to try Intuniv - you won't really need the same dose as before, so no need to push it.
Or, if you want to try something experimental, or a Racetam, then go with Fasoracetam! = ) We have a fairly extensive thread here on Longecity. It's a compound currently in clinical trial for treating not just ADHD, but the comorbid diseases as well.
http://www.longecity...55-fasoracetam/
PS: You're welcome to check out my ADHD master-thread as well, in fact I welcome any and all feedback. And feedback definitely helps with the motivation.
http://www.longecity...ception-thread/
The main idea, is to collect all of the Longecity knowledge about ADHD, into one simple, clear, and extensive thread.