Thanks for sharing all of that shinsplints - what's your name?
You are a complicated specimen my dear and i am sure i do'nt know the answers. But there are some clues in what you've written that might be worth a closer look eg especially the way your mother reacted to finding your pills. That looks alarming. You are an adult. How can it be right for a mother to force you off something thats working for you.
I haven't the time right now to go through your post with a fine tooth comb.
But here's a few things that i thought:
Try to get a proper diagnosis from a psychiatrist not a psychologist. Tell your gp you want a diagnosis. I don't think they can do a really great job in only one session either so i would try to have a few more sessions. Go to a psychiatrist who does therapy.
I don't know enough about autism to comment on it but what i do know is that smart people can have personality disorders. Personality disorders often make it difficult for people to get along socially. The whole area is totally fraught though and you should tread carefully.
It sounds like you are doing well in your job and its a shame that people aren't seeing it. If that was me, i would have walked out by now. I wouldn't have been able to cope with all the flack. I get so stressed by people's bad reactions when i am trying really hard.
About your headaches, perhaps its not the lack of sugar that causing it but the lack of caffeine. If you eat a lot of chocolate, you might just have a caffeine addiction. Maybe this would be worth discussing with your GP. How to quit sugar and yet only gradually ease of the caffeine. Do you drink much coffee, perhaps you could drink more tea and coffee in lieu of chocolate. But at the same time, be very aware that you need more water.
Are you drinking more water when you diet? How much do you try to drink? You should drink 8 glasses of water a day not including tea or coffee. I know if you do drink tea and coffee this would be very annoying as you will always be running to the loo. Hence why it might be a good idea to discuss options with a gp.
About autism again, have you ever seen anyone about that condition to see if they would diagnose it? Don't autistics lack feelings or are less susceptible to feelings.
It seems to me that what you have said about antidepressants indicates that they make a positive difference to you. I only take one pill. What med did you try. I take Effexor and its great for me. Some antidepressants increase appetite such as prozac. Effexor doesn't . You need to make sure you get one that does not increase your appetite. Effexor is quite a strong med and many people do not feel good on it but except for constipation, i love it.
When i come back from my trip, maybe we can chat on the phone.
About writing, i disagree that you couldn't make a living from writing. You need to find a subject though and become an authority on it.
I wanted to write a book about my cycling journeys in india but i decided i wasn't a good enough writer to do the project justice. I probably didn't give myself enough of a chance but its important to believe in the possiblity of something to have a chance of achieving it.
I wrote a fair bit, and of course it would need massive editing. I understand the process of writing. Now i am just happy to cycle, keep a diary, take pictures and share the stories with friends and other interested parties in a less formal way.
I don't even keep a blog but that's because i get so frustrated trying to set a blog up that i can't do it. I need someone to do it for me so that all i have to do is write in it. I must be the stupidest person alive because even teenagers have no trouble doing it.
That's all i cna think of at the moment. Its breakfast time.
I was doing strength training every second day until a couple of weeks ago but then stopped. I plan to get back on it soon. Right now I'm just trying to focus on getting my hormones/fluids in check. The drugs I was on really messed up my body in more ways than one. It's gonna take time. 
(I'd pay you of course 
)