Wondering if I am autistic and thinking of requesting a diagnosis

Hello everyone

I just wanted to introduce and say a little about myself and ask a specific question which I feel may be related to any diagnosis I get.

I have had on and off thoughts over the past two to three years about whether or not I have autism at some level, ADHD or maybe both.  I have put off doing anything about it other than a chat with my doctor about ADHD which I did not follow up, because I feared for my employment prospects and it's just been so long now since that chat. There are a few reasons I have been thinking. Many of the common reasons which I won't bore you with here, but particularly:

My brother was diagnosed a few weeks ago and we are so alike in so many ways it is making me think even more.  He is 10 years younger than I am (40) and we are both convinced our mother is autistic.

My sister is fighting for assessment for one of my nephews and the other nephew from another sister is now an adult and has very similar traits to my brother.

I've done online autism tests twice and scored 28 then 26 today. I have also scored very highly on bipolar tests. I have had therapy for depression, but I am always pushed down the childhood route of discussion with therapists blaming everything on that.

Anyway, my question... is the below something that people with autism relate to?

I am really struggling academically and I would like some opinion on this so I can mention it during a visit to my GP.  Basically, I really, really struggle with applying theory to real world situations.  I understand all of the theory. I understand all of the real world situations. I just cannot apply one to the other except at a basic level. So it makes writing reports a real struggle. I am coming to the end of a foundation degree in a professional subject which is work based, so I know many of the real world situations so well.  Earlier on in the course it was lower level stuff with a much more narrow range of theory, so I could just about manage, especially with it being much more explicitly stated in the course material. Now that the expected level of theory is much wider, being unable to apply it is causing me a lot of distress. Additionally, I keep having annoying thoughts constantly, such as 'if I am writing a business report, why do I have to keep explaining, referencing and citing really simple concepts that anybody who the report is of interest to would know'. It makes it feel odd - unreal? I want to pass the course because I just want to better myself and complete something worthwhile for a better future for my wife and I.

I don't think I am a mastermind, but I don't think it is an intelligence issue.

I can perform in subjects like history, where we are dealing with issues that are events and facts. Might explain why it is my favourite subject! I found the AAT Accounting qualifications relatively easy because the answers are 95% exact and rules / reconciliation based.

As a child I could read before I started school and could spell extremely well. To the point I often couldn't get on with my work due to people interrupting me to spell things and I had an obsession with maths and memorising things until I was 9-10. And a vivid imagination (now gone). 

This was lost due to severe emotional abuse from my mother as a child from about 7. I just didn't care about passing anymore, although I did pass until the 2nd year of A-levels without even trying, then failed the A-levels I would have passed if I had tried. We did see psychiatrists some 30 years ago but it was never so much about my need as the needs of my mother trying to convince people of my flaws.  So I was never assessed for anything like this and we never got to the bottom of anything.

Sorry for the long winded read, I just had to get it off my chest and ask for some help understanding.