I remember when I was about 16 or 17, and I was definitely more autistic with some people than others. I started sixthform and had to spend half the time at a different school- so when I was at the "normal" school, I was far less aspie than at the new one.
I tried to mask my autistic nature with most people at my normal school, except for with my few friends who were weird like me!
At the new school, however, it was really hard (I seemed to get more autistic starting from age 12 to about age 21), and I was doing A Levels in French and German there (BAD choice!). So anyway, my new teachers thought I was really quiet as I had serious problems with my selective mutism for about 18 months starting then so was appalling at communicating. The strange thing is that they never even wondered if I was autistic, although it was really obvious I was then.
So, yes, in some situations I was more autistic, with some people I was less.
And, yes, it was partly because I was a teenager, as the OP suggested- crazy hormones maybe?
Now, I try my best to hide my autistic nature at work, especially when I have a classroom full of children, but I can have problems when dealing with the other staff- I'm either really chatty or really quiet, depending on who it is.
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Depression, GAD, Social Anxiety and unidentified mental health issues too
And now OFFICIALLY DIAGNOSED!