No informant for assessment, previous EUPD diagnosis

Hi all,

I won't tell you my life story. Basically, I've felt out of place my whole life. I'm now 33. Diagnosed with emotionally Unstable Personality Disorder a decade ago but never agreed with the label because I never had a fear of abandonment. I don't know what that means, because I prefer to be alone. Ever since I was diagnosed with that it's like a black mark on my health records. It's an awful label.

Anyway I finally have been referred through right to choose. The only problem is I do not have any one who can be my informant. Literally no one. I don't have a relationship with my parents, reasons I won't go into. I was bullied at school and had no friends and as an adult I choose to isolate myself. Its just easier that way. 

I was hoping an assessment would give me answers. I've suspected autism for years. Recently I've felt constantly burned out and overwhelmed, just reaching a point where I can't cope with working, going to the shops and everything. Every single day is a sensory nightmare and it's got worse with age. I have got adhd too, which isn't helping stuff I think. I feel I need to go part time for my health but I just can't afford it. 

Anyway I've gone off topic. I understand it might be hard to get a diagnosis without any evidence or any informant, and I don't have any school reports or anything either. I literally have nothing. I'm feeling very overwhelmed and defeated to he honest. Why is it so hard to get a diagnosis? Right to choose is my only option because I can't afford private but it seems it would be a waste of money anyway.

I do not want to put myself through an assessment if it would be impossible to get anything out of because of a lack of evidence and I'm thinking of cancelling the referral altogether.