Why I didn't know I was autistic

I've been thinking recently about why I never thought I might be autistic until I reached my early fifties.

The first reason is that I didn't know what autism was, having grown up in the 1960s & 70s. I remember seeing "Rain Man" as a young adult, which is apparently what some people use as a stereotype for autism, but I just thought he was a savant. 

I thought I was just a "normal" girl and then a "normal" woman. As a child I didn't have any developmental delays. I slept well. I wasn't fussy about food. I was good at reading and spelling. I enjoyed books, art and crafts, music and dance, and loved animals. I had some friends. As a young adult, I liked being at home but did also like to see friends and occasionally go out for dinner or to the cinema or a concert. I didn't stim, I didn't have any obvious problems with eye contact. I didn't like school and was bullied for a while as a teenager, and as an adult I was manipulated by and had misunderstandings with friends and family, leading to breakdowns of some relationships, but I just thought that happens to everyone. I did always have trouble controlling my emotions and cried a lot - but I was just sensitive. We're all different - right?

So, what is it that makes me autistic?I

Here are some clues:

As a child:

I had an imaginary friend (and later, an imaginary horse)

I had gastro-intestinal problems from a very young age

My reading was so advanced I was probably alexythemic (but nobody knew what that was then)

My interest in horses was obsessive (I read everything I could find about them, drew them, collected models of them)

I taught myself to play guitar aged 11

My friend groups changed a lot over the years and I was generally not invited to parties, or even to other friends' homes - I mostly only mixed with them at school. It didn't bother me.

I preferred the company of younger children, and of adults, to kids my own age

At junior school one day, on observing the rough and tumble play and apparent lack of empathy of some other children, I wondered if I was the only real human and they were all robots.

Despite being fairly intelligent, I under-performed at school and didn't do well in exams.

I always suffered in cold temperatures (if I get too cold, it registers as pain)

As an adult:

I now realise I censored my conversations with other women to suit their interests: mainly talking about clothes, hairstyles, make-up, celebrities, popular tv programmes, etc. Not mentioning my interests in sci-fi, Stephen king novels, music, computer games, etc.  

I was always a "people pleaser" and I didn't know how to say "no" to a request, and ended up going to quite a lot of social events I didn't really enjoy.

I changed jobs a lot, due to problems with working relationships and feeling picked on by managers.

I've had lots of special interests over the years, including social sciences, food & nutrition and Interior design, and my main interests at the moment are reading fiction, computer games, and autism.

What were your "clues"?