From what I understand it's not a lack of dopamine receptors so much as one's dopamine reuptake system being "too efficient" -- effectively cleaning up the dopamine before it's had the opportunity to actually finish doing its neurological job.

But yeah, ADHD in particular is a very multifaceted, complex, and nuanced topic. Being a neurological disorder already makes it such, but the way it intersects and interacts with social contexts makes for such a large variety of manifestations, many seemingly contradictory.

I did mostly fine as a kid because structure was imposed on me by school and parents...and because I had intense rejection sensitivity (and validation euphoria) which shaped my coping mechanisms. Yeah I hated and procrastinated on homework until the very last minute, but I'd ultimately do it because the prospective shame of teachers and parents being disappointed in me was overwhelming. Yeah I'd fidget, but to save myself from attention and embarrassment I'd keep them subtle and unnoticeable by others, like little tiny finger movements (imagining I'm playing an instrument -- in my case initially the recording and then the violin). Yeah I'd daydream and lose focus in class, but if there was a chance the teacher would call on me to answer something I'd be laser focused -- don't wanna disappoint.

Because of this no one knew I had ADHD, including myself. Always just figured I was just a "creative daydreamer" and "sensitive hopeless romantic". Never even considered the possibility as all I knew was the stereotype of hyperactive disruptive children with poor grades who couldn't focus where I was the opposite: a quiet and reserved kid with good grades who would hyperfocus on a good book or video games for hours (gee who would've thought that hyperfocus on things you're very interested in is itself a symptom of something called "attention-deficit" disorder.)

In middle school my family and I suspected social anxiety and got some SSRIs to medicate which ended up being terrible (made me feel incredibly apathetic to everything.)

And so for the longest time I figured I was just doomed to be an introverted socially anxious person.

Then adulthood came and I lost the externally imposed life structures of childhood and just fell apart. Still took me a decade to figure out I had ADHD, but in retrospect it all made so much sense...and my so-called social anxiety was primarily me subconsciously leaning into my rejection sensitivity as a coping mechanism to fight against other ADHD symptoms.