My family is not at all like yours, as my parents are pretty liberal with trusting me and they respect me a lot because I reespect them yaddyada so things may be different between my point of view and yours.
What you should try doing is being "on top" of these conversations/arguments, not in the sense that you should be better than everyone else and be the best, I mean rather taking control of the conversation, like for instance in the Netflix convo, a good response to the aftermath would've been something like "I asked you about Netflix, not how our family is doing and your approval of your children", you have to be the most reasoned and calm and precise.
For instance, my family used to be in loving shambles bc drinking and stuff but that's not the point, the point is, that it got so bad that my little 12 or 13 year old self had to take control and be the "adult" of the situation, which would be me confronting the situation as head on as possible and being as involved as can be, regardless of my knowledge to the situation. But due to my interfering in those arguments, there was essentially a counselor created, and now in any argument that takes place I interfere and ask what's going on, how it can be solved whatever the forget, and just doing that over the years has actually helped my family out a lot, there's no more drinking, arguments are very rare, and everyone's happier for the most part.
Basically, you have to be involved when these things happen, but it also requires the mental and personal capacity to execute this, you have to have the knowledge and confidence that you are in control of the argument. If I were to be locked in the car and my sibling started asking me that stuff, I would've acknowledged how passive aggressive she can be and how stupid and stuffty it can be and how talking behind peoples backs does no good etc, if she were to get mad and yell or whatever for what I said, or offended and hurt, then I would've had to stay calm and rational and either explain how they're overreacting or how I wasn't trying to hurt their feelings or what have you.
it obviously may not be as easy for you, you said yourself you're a bit quiet, but I was too until I realized that things wouldn't change until I did somethin bout it.
tldr: be involved and counsel and confront everything when dumb stuff goes down, and no matter how negative it gets, just remain rational and calm.
