Since you mention laziness and low motivation, I wonder if you have the same problem I have. The best description I've found for it is "a weird urge to not do things." (If you're interested, I've written everything I know about it here.)

I consider it an unofficial ADHD symptom. Lots of people on the ADHD site I go to describe the same problem, and it's closely related to what ADHD is understood to entail, but it's not explicitly in the diagnostic criteria and you will find almost nothing about it in professional literature regarding ADHD. I only found out the name of the problem (initiation impairment) from reading about the same symptom in another condition.

I've found ADHD meds helpful. Since you have other ADHD symptoms as well, that seems like a promising avenue for help. The only similar drugs I know of that are typically legal without a prescription are caffeine and nicotine.

I would take any info on specific neurotransmitters with a grain of salt. Diagnostic labels aren't based on them, and even treatment is only loosely related. Most ADHD meds raise dopamine, but atomoxetine (Strattera) is an SNRI instead, and I've heard anecdotes suggesting that it helps a lot of people with this problem (although, it didn't help me personally).