My parents think I'm not autistic, now what.

It appears to me that the only way that you will gain any certainty is to have a clinical assessment for autism. Your uncertainty seems to be having a more deleterious effect on you than either finding out that you are autistic, or finding that you are not autistic, would have. For comparison I scored 37 on the AQ50 and 167 on the RAADS-R tests and was diagnosed with ASD about 20 minutes into my autism assessment. I found that being diagnosed was a great help for my peace of mind, I had a concrete reason for my sensory traits, difficulties with other people and limitations.

Many parents of autistic people are resistant to having their children diagnosed, this is because they think that it is somehow their fault, a reflection on their parenting skills, which it is not. Autistics have a different wiring to their brains and somewhat different brain function to that of neurotypical people (different not less). Parenting has no effect on brain architecture, except in cases of horrific levels of abuse to babies and young children, which I am sure you didn't suffer. 

If you or your parents think that a diagnosis of autism might have a deleterious effect on you then reassure them that it will not. If you are autistic, then you will be autistic, with or without a diagnosis. Fairly obviously not knowing is not a good place for you and you can argue with your parents that knowing, one way or another, can only be good for your overall wellbeing.

If your parents are worried by stigma holding you back, then my daughter, who was diagnosed autistic at 19, with the help of accommodations from her university for her autism, gained a first class degree in chemistry, came first in her year, and won a Royal Society of Chemistry prize. I'm also autistic, have a PhD in molecular biology, and worked until my retirement in scientific research at leading universities. I'm also a fellow of a learned society that Sir David Attenborough and the ex-Emperor of Japan are also members of.

You are better off not thinking you are autistic. 
Labelling oneself autistic is an insidious way of giving up on life.  In my experience I was diagnosed - wrongly - as autistic a few years ago. 

I don’t even want to bother with relationships and I blame that on the people who diagnosed me. 

If  people who are not autistic are mistakenly diagnosed as such  their lives will be negatively affected. 
Forget post office scandals: the industry of uncriticisable diagnosis of autism as if it was a perfect process - the panels apparently never  get it wrong - is a scandal. 

I did that one too, and I self scored 175/240 (threshold 65+) which is nearly 3 times the minimum threshold (2.7 times to one decimal place, if you like accuracy.) I haven't had my mum fill it out yet. My mum got upset at doing the test though because she thinks it's her fault the way that I am and also she seems to be answering highly for herself on a lot of the questions.

I'm just, I don't even know how I feel (it's like a blank in my head I can't describe the word. It might be similar to fustration, fear and sadness of the unknown, but I can't be sure,) that I will never know if my problems are ''legitimate'' that I will constantly have to ''prove'' my difficulties to people - even harder is that when I'm asked for specific examples, I find it hard to say (yet, I can write them down okay.) I will never know if my problems are due to biology or the medically traumatic upbringing or, as you write, maybe it's both.

There's just something ''not right'' when I try to communicate with people and I am always made to feel by my parents (and other people in public, but I tend not to talk to public people long enough to find out) that there is something ''wrong'' with my communication style. Yet, when I mention this to my parents they say ''I'm fine'' - so why are you always correcting the way I behave and speak to others (!) It's not like I'm rude to anyone, parents just tell me I've ''taken something the wrong way'' as I always have done - which is a problem, especially since I can't work out what the ''right way'' is meant to be.

I'm so ... well, I'm tired now. I'm ''allowed'' to be on laptop past 10pm since my dad is also downstairs on call out. I really should be going to bed now.

Thank-you,

Jayde.

Autism is largely genetic, but it has an environmental aspect as well. Some identical twins can have one twin autistic and the other not. Difficulties in labour are often cited as causative of autism, one of the major components being low oxygen levels. It is a legitimate possibility that you might have become autistic, or perhaps 'more autistic', through oxygen starvation.

Lack of neural mirroring is a rather challenged concept in autism see here : https://pubmed.ncbi.nlm.nih.gov/24515797/

It is well known that autistic people with average and above average intelligence, especially females, put huge effort into studying and deliberately copying other people around them, especially other people who seem to be socially confident and successful. Therefore your copying of others is entirely consistent with being autistic.

I am diagnosed with ASD and I have neurotypical friends, some I have had since schooldays, I also have a neurotypical wife. I was diagnosed very, very late and spent the greater part of my life not knowing, or suspecting, that I was autistic. This lack of knowledge did not stop me making friendships. My autism, and lack of knowledge that I was autistic, caused other problems, but not that.

Try the RAADS-R autism test, it is the most definitive, it can be found here:  https://embrace-autism.com/autism-tests/