That's nice that they are just surprised and not upset. Do they easily remember afterwards not to interrupt you? Or do you have to ask again?

And yeah, my family is pretty loud too. Not that I mind. I'm used to having to match that loudness. Just when I'm low it's harder for me to match it. And I've been having a lot of stress so I've been pretty low pretty often. And when I'm realllly tired I just feel like I have zero energy left for it.

Your mother sounds like, she's got a really sh**ty attitude yeah. It sounds like to me, she was going to feel blamed or "bad" unless she chose to attack and that's what she did. What I mean is, she probably gets to feel upset and negative, feeling like she was asked if she's having a bad attitude by thinking what you are saying is unimportant.... (even tho I get it that that wasn't your intent) so then she decides to actually take on that bad attitude and outright say so, that yeah, she thinks it's unimportant.

My family doesn't get this extremely defensive when I ask them to pay attention to my being low. They do try to understand. Even though I do feel like it's weird when I ask like you said it feels weird for you too. But I would say they can still get upset if they feel criticised. And as far as I'm aware it's normal for most people to get defensive if feeling criticised. Maybe not to the extreme like your mother does. Narcissistic anger is more extreme too.

But I've read about this kind of issue, and so I've been trying to convey stuff to them without coming off critical. Maybe you could try to ask your mother why she interrupts you, is she like too excited or whatever else you can think of that sounds like it could work. Like making your stuff sound like you are genuinely trying to understand her before you try to ask for whatever you'd like from her. By the way I've read that kindness works best for narcissistic people in general, while keeping your boundaries, too. (I've read a book on the so called High Conflict Personalities. Maybe it would help you too)

Also yeah, walking away, it's like I've tried this on my bf recently, I tried to tell him a couple of times that I'm not okay with whatever paranoid negative words he's used about an issue between us. It didn't help enough, so I told him I can't talk to him until he gets what I mean, because it would just lead to more arguing because this way there is no way for either of us to calm down. So I didn't talk to him. And that seemed to help....for now. Like he went like, yeah he sees what I mean. He hasn't said anything negative since then.

Weirdly enough I DO feel like this is on topic too like you said you relate it to being able to open up more....I'm not sure how it relates in my case but I feel like it does, because I wanted to connect more with some people and then I started being bothered by stuff like this. I used to just be like, ah nah I don't care, or like I can just fight back and match their loudness (not in a bad sense!! I would enjoy it fine before I got too stressed in life), but I was also more detached. And me asking family to please pay attention when I'm low, that's actually a kind of being open too