I study ADHD and have a background in neuropharmacology, i.e. how certain conditions (and medications) affect on serotonin, dopamine and other receptors in the brain as well as the activity of pathways between different areas.

This sounds like an appealing hypothesis on the surface, and based on some brain imaging data (which has the benefit of being visible on brain scans), but it doesn't necessarily hold water as its own distinct condition. The main issue with this is that most of the features you listed fit under the well-established diagnostic criteria for ADHD, with the others fitting under the very common comorbid disorders of ASD, ODD, anxiety, depression and bipolar. All of these have been found to share common genetic risk factors. This means if you have ADHD, you will be likely to have at least one other disorder, and have some traits of others (in fact it's the rule rather than the exception - most people with ADHD meet full diagnostic criteria for at least 2 other disorders, and many meet criteria for 3+).

Any qualifiers like "may or may not be hyperactive" simply represent normal variation in symptom clusters in ADHD, just as people with bipolar I have more manic episodes whereas those with bipolar II have primarily depressive episodes. It feels like it's trying to answer a complex and confusing picture of heterogeneity and comorbidity with a conceptually appealing but oversimplified label.

Also, the alternative treatments may seem helpful but are untested, and are somewhat contradictory. E.g. You say SSRIs can make symptoms worse, but then you say increasing serotonin lowers hyperactivity in the brain (??), and anything that depletes/lowers serotonin could worsen symptoms. This is wholly contradictory. Incidentally, stimulants and alcohol do not decrease serotonergic activity - they indirectly increase it. There's a lot of contradiction there.

I'd recommend reading more about the way SSRIs and other drugs work in the brain, and read about the brain differences seen in ADHD, ASD, bipolar, etc., and you'll see that the picture is a lot more complex than certain alternative treatment clinics would make out.