Oh boy, all this talk about interoverts can cause people pingenhole thenmselves. The truth is there are many other factors that can lead people to act in certain ways.
For example some people have a tendancy to move away from things: like pain. While others move towards things: goals, etc. Some people are proactive: they initiate. Others are reactive: they respond. There are internal people: they judge things based on their personal universal concept. There are also external people who gain value from others and the outside world. And still things are not black and white. Some people may be very social in at work and meek in social settings. It's complicated
On top of this, trauma can play a major role in influencing people. I understand that you, Gilda, don't get allong with your parrents to (to say the least) as such you could be afraid that others will reject you in a similar fashion.
Now you talk about the stress of dealing with people. Something I can't put in perspective. But if you would allow me to hazard a guess, perhaps you had to deal with judgemental people in the past and you had enough of it for a lifetime.
So, what I should have said to make this short is that there are many variable out there.