back again, eh
well about the Q's
seconding kyupol on point 1. obviously seek professional consultation and not just "people on the internet" coz no ones really certified but there's books about it for personal research if you feel capable of like doing it
point 2: I am not officially diagnosed (wouldn't mind at least a consultation tho i think it'd help) but honestly my method is just having my setup ready to go so when the mood to create strikes i can capitalize on it rather than dragging through turning on devices, finding notebooks and pencils and so on. plus just having a notepad (physical or the app) open so when an idea strikes but i dont feel motivated to draw/write it i can at least jot it down to reference later and specifically somewhere i know i can find and go back to it again.
lately (for me) that's been a private discord server with just me in it to stock notes and i've got channels specifically dedicated to each of my projects and separate inspiration/reference channels (screenshot for reference)

it may seem like overkill to some but as someone who understands that my thoughts can be very all over the place at any given time having a space where things are organized is convenient
and point 3 just sounds like plain old overthinking which makes sense when you take into account the auADHD traits so it's really gonna boil down to just forcing yourself to get out of your own head, which sounds difficult but i realize i do myself a lot of favors when i'm drawing for example and if something looks bad and i start to obsess over that minor detail i just go "hey that bits not important now. lets work on the overall piece then come back later if it still looks off" and 9/10 leaving it be and just pushing through till i'm done has been a lot more beneficial or productive
it also helps sometimes to make "quality" your last priority or at least thats something i've been working on lately.
"doesn't matter if it looks bad, doesn't matter if it doesn't flow perfectly just finish it and then do all the touching up later" as the mindset has worked because instead of worrying about whatever the focus is just getting it done
not to give homework coz i feel like you struggled with folks giving suggestions and you turning into a whole "side quest to check off the list" but today just so happens to be "make a terrible comic day" so if you want to [not you have to] you could try throwing together a random crappy 4 panel comic no goal for quality no point just slap some stuff together and call it a day
like this is one example from the tag on twitter
https://x.com/jlee4567/status/1805324860773777767

but it's literally focused on just making stuff quality be damned which i think is something we as artists need every once in a while
and apologies if this got ramble-y that's one of my little brain quirk habits but hopefully you can find a way to work through your funk 