What you are saying in all your comments is perfectly consistent with how I've heard people say about their experience as asexuals. Have a read of asexual literature, maybe post on a few asexual forums with your experiences.
At the end of the day, I am 100% sure there are people with similar experiences to you who call themselves asexual and also who call themselves allosexual (not asexual).
At the end of the days, these labels are a personal thing, like deciding how to cut your hair. There's no right or wrong way, just what makes you feel good.
My advice is don't stress too much about labels.
I'm a woman who dates in kink-adjacent circles, and I'm a dommy switch so I have seen a lot of subby guys' profiles. You seem pretty normal, you seem like the sort of guy I date, down to the social awkwardness/lack of experience. I have a goddess kink so your specific fantasy is right up my alley. There are lots of women like me.
I've dated men who have been pretty normal but just didn't enjoy vaginal sex, we still had sex but just not PIV. I've dated men with fetishes who also enjoyed sex.
If you WANT some labels, the different types of attraction might speak to you:
As you said about the painting, it may be that you are attracted to women in an aesthetic way.
The good thing about labels is that people don't generally police them too hard because they're never perfect; I myself identify as straight but it's not a perfect label for me, just very very close.
If it makes you happy to call yourself asexual or demisexual or whatever, then do it, try it on. You can always change your mind later. Maybe try joining local ace groups and talking about your experience with them, or reading through relevant subreddits.
Why don't you phone around GPs and ask to find one who will give you AZ? My brother is 29 and in Perth and was able to get AZ in early July that way. I'm sure you'll find a doctor who will do it for you, unless you live remote.
Something I found very interesting/important in the book that you skipped over was the bit at the very beginning where children were asked what they wanted from their parents, and rather than asking for more extracurriculars or later bedtimes or anything like that they said that their parents seemed stressed/sad and they wanted their parents to be happier. I found that very lovely/compelling.
I played mafia on the xkcd forums for a while (and it's restarting on the new xkcd forums: https://ramenchef.net/nxf/viewforum.php?f=6 ) and I quickly came to realise that I wanted to have fun, and attempting to do everything optimally to have the best chance of winning wasn't necessarily the most fun (because it has a huge cost in reading pages and pages of game content).
I enjoy the logic puzzle aspect (how to best use powers/resources, what can contradict each other, etc) but not the social deduction. Same with other games I play, like SH or The Resistence.
So in the end, I don't take it too seriously. I have fun, I play my way, because of the vibe on the xkcd forums the people there accept my attitude (or are frustrated by it, but in a friendly way?), and it's a kind of win-win situation. When logic puzzle stuff becomes possible I hook in on that and try to work things out.
Mostly I find I enjoy moderating (running) games, and am currently modding one which is having a really good reception.
So yeah, my advice is to think about what you find fun and do more of that. Mafia isn't meant to be a chore. If you find a particular type of analysis fun, do it.
I would recommend forum mafia as a pasttime to people, it's chill and there's a great sense of community/comeraderie.
Why don't you just use beeminder, but set your goal to be flat? So say you're brushing your teeth, you can tell it you want to brush 0 times a week, when really you want to brush every day, and you end up with a normal-looking graph with no problem if you forget to log (because you can just backdate the data!)
Also has the advantage of letting you use it the "traditional way" (with a slope and a pledge) for a goal that can be done automatically (e.g. duolingo, word count on a writing project, whatever).
You are almost certainly getting enough iron in your diet as a person who (presumably) doesn't menstruate. If you are not feeling fatigued or dizzy on the regular, you almost certainly have enough iron. If you are worried, get a blood test, don't just supplement willy-nilly.
I would recommend you do a food diary for 3 days and enter into chronometer or myfitnsespal. You are probably getting 10-15mg of iron a day and the RDI for adult men is 8mg. Yes, vegans get non-heme iron, but the iron in meat is something like 80% non-heme, so most people actually get a very small amount of heme iron, and diet tends to have no impact on iron intake.
I speak generally as I don't know what your diet looks like: if you eat pizza pockets and ben & jerrys for every meal then you have bigger problems than your multivitamin.
I'm a vegan doing a nutrition degree (at an accredited university, not at one of those woo-woo online holistic centres). I also have low iron because I have dysmennorhea, which I assume you can't suffer from.
Definitely take b12 and take D if you don't get sun (you probably don't). Make sure you are getting vegan D if that's important to you, most D is not vegan. Also make sure the D is an appropriately high dose, not the very low doses that are in multivitamins.
[epistemic status: i have formal education in nutrition, and this is remembered impressions i got from professors/experts, but may not be correct, and is almost certainly simplified and lacking in nuance]
In our parents' generation, boiling or steaming was considered the most healthy way to prepare vegetables: fat and salt were the enemy, and especially steaming left the vitamins in (rather than allowing water soluable ones to leach into the cooking water).
Our parents cooked vegetables in this way because they learned it was the healthiest and they wanted us to be healthy.
Nowadays the nutrition Powers That Be have acknowledged that yes, steamed broccoli is a little healthier than roasted broccoli or broccoli sauteed in garlic oil, but steamed broccoli only tastes okay while roasted broccoli and sauteed broccoli are both damn delicious (epistemic status: broccoli is my favourite vegetable). The wisdom from on high is now that vegetables should be cooked in appealing ways, and the small loss in nutrients is nothing compared with the large gain in flavour which encourages people to eat vegetables which then means that people are less likely to eat e.g. big macs and tater tots.
I think as well as what others have said, an ethical consideration with placebos is that they are treating someone with something that they know doesn't work. Like, basically, on some level, it's ethically dubious to make you go to all the effort you outlined, interact with medical staff, receive an actual injection, etc, and deliberately not treat you. That's why many many trials have "stopping rules", where if it turns out the treatment is working really well, the placebo group gets it, too.
My impression is that my period symptoms are maybe in the top half of severity, but not the top quartile?
Don't compare yourself to others. It's a very common problem that apparently women especially have. You have symptoms that are distressing to you and are more than you want to experience AND THAT IS ENOUGH.
FWIW, I would definitely say based on your description you would be in the most severe 5-10% given when I am bitching about periods with friends who menstruate none of them talk about being out of action for 4 hours a month.