I need help

I apply for PIP a few months ago, and I received it without much hassle, I have a line that I took with the process but I did not plan for it as such. 
Autism is ultimately a neurological condition, so the correct line to take in application is to help the reviewer to see that you are not seeking PIP for reasons of stress and moodiness in daily-life, but the help the review see that you have a spared-cognition that has meant that there is inequality in not having PIP. 
I highlighted how display the aspects of the triad-of-impairment, I highlighted how I have restrictive-and-repetitive-behaviours, I highlighted how I display sensory-anomalies and sensory-processing issues. 
At no point did I seek to make an emotional-argument, where I used autism-related jargon, as I pointed out the features of my difficulties. I made it quite clear that I was not seeking to degrade myself, but that I was trying to seek remedy to a inequality as a result of disability, I was seeking fairness in my pursuit of independence.
I used the citizens advice examples to format the points I was making, I only made a point in the name of highlight a severity or frequency of a difficulty. I only used any manifested-behaviour or psychological-issue or developmental-issue to describe the knock-on effect of my neurological-aspects of autism.
I hope this helps, if you need a more specific prompt, please state it and I creepily as best as I can. 

It has been about 3 years or so since I last applied, but they said to explain what it's like on the worst days of my life, which I thought I explained well backed up with the evidence last time. But it seemed they just glanced over it and ignored everything I said and just denied it straight away. 

I didnt have any other notes from anyone else though at the time as I had no external help with the claim and process as I explained in the application as I don't have any kind of support network. Even my own family wouldn't help me with the application or write letters to help. 

They even stated in the rejection letter that I have an extensive knowledge about autism and how it effects me...and that just was like a "well yeah? I live with this day to day? But i understand that i have difficulty explaining in detail what difficulties i have, as ive been told for all of my life that everyone has this difficulty,  but i just seem to experience it at 1000% rather than "normal" " 

It was all very confusing and frustrating to be treated like I was making it all up.

When you say that ‘they said you have extensive knowledge of autism’, that makes me think that you may have a wording issue, that you may be talking in the third person or speaking about yourself objectively, rather than speaking about how that translates to your daily living.  

For example: “Do you having trouble getting dressed?”, instead of saying ‘no’ or ‘I have RRBs i.e’, you say “I have trouble getting dressed everyday as it takes me over an hour and cannot be completed if there is something missing or out of routine. Additionally I have trouble finding clothes that are appropriate; because I have to get them from a specific place due to RRBs, SECs, and Sensory sensitivities that cause me pain if I wear the wrong materials; this impact my daily living and employability everyday.”

Something like that, you have to make sure that what you are answering the question to suit the process of assessing mobility and daily-living criterium, which can be difficult when we are monologuing. It’s ironic that the PIP doesn’t take our SECs into account, while they are interrogated us about our autism, we have to overcome our autism to prove we have autism, which is crazy because a key component of autism is being unable to affectively communicate..!

You have to be socially and emotionally unimpaired, you have to say how you are affected and affect others, to evidence that you have a social-emotive-communicative impairment?! So to reiterate, I think I understand the issue, so I would suggest that you exposed yourself to example answers and really consider how a thing affects you.

For example: “Do you have difficulties managing toilet needs or incontinence?”, instead of saying ‘no’ because of the phrasing of the questions and the mobility-oriented prompts, you say “Yes, I have difficulties with hypersensitivity that mean that I am unable to use public WCs in most circumstances, which can mean that if my routine does not or cannot factor in these sensitivities, I either cannot do the thing or can be in in pain for most of the day, this effects my daily living and Mobility everyday”.

The questioning of the PIP is tailored to thwart those with hidden disability, the above being an example of my difficulty was an answer that I was not supported to make, despite stating many times that I have SECs that make it difficult for me to stay on task, as I tend to monologue if uninterrupted. The PIP process does not factor in social reasonable-adjustment for autists very well..

You have to be socially and emotionally unimpaired, you have to say how you are affected and affect others, to evidence that you have a social-emotive-communicative impairment?! So to reiterate, I think I understand the issue, so I would suggest that you exposed yourself to example answers and really consider how a thing affects you.

For example: “Do you have difficulties managing toilet needs or incontinence?”, instead of saying ‘no’ because of the phrasing of the questions and the mobility-oriented prompts, you say “Yes, I have difficulties with hypersensitivity that mean that I am unable to use public WCs in most circumstances, which can mean that if my routine does not or cannot factor in these sensitivities, I either cannot do the thing or can be in in pain for most of the day, this effects my daily living and Mobility everyday”.

The questioning of the PIP is tailored to thwart those with hidden disability, the above being an example of my difficulty was an answer that I was not supported to make, despite stating many times that I have SECs that make it difficult for me to stay on task, as I tend to monologue if uninterrupted. The PIP process does not factor in social reasonable-adjustment for autists very well..