Interpersonal dynamics are typically highly problematic for traumatised people. It's because of arrested development after having been brought up in a dysfunctional/exploitative/abusive environment. If you've never been taught how to manage social dynamics, you can't NOT be quite emotionally immature as a result. After being raised by grossly immature parents, I never learnt how to deal with life in a reasoned, mature fashion. I'd never been taught the necessary skills to cope with increasing challenges and complex situations, especially social ones. I had an inordinately juvenile perspective, which limited me in many ways.
It's NOT your fault that you find social interactions stressful and perplexing and overwhelming! This is the logical outcome of extreme stress, especially on a young child whose development processes have been distorted.
What I've found helpful is to literally change the way I speak. Start sprinkling simple statements throughout your day like 'I want _______' or 'I like/don't like __________' or 'I feel ____' or 'I'd prefer to ___________' as a way to offer opinions or observations that demonstrate a preference. This can help you get used to expressing yourself in basic ways that were likely discouraged/suppressed as a child. It'll feel weird at the beginning, but it's quite possible with practice to toss these off casually, as if in passing, as if it's not really a big deal to let ourselves be known in these little ways.
Go into shops and speak in simple statements: 'I'd like the chocolate ice cream!' 'Nah, I don't like that colour'. 'I want an extra-large cappuccino, extra hot, pls!' When speaking with people, find a way to express a feeling: 'this sunshine feels great' or 'I love the sound of a rainstorm'. Even when you're alone, practise speaking in these declarative ways so that you start feeling good about expressing who the hell you ARE! :) If you have a good friend/sibling/anyone with whom you feel safe, deliberately orient your speech in this way.
I realised at one point that I would never express a feeling/opinion and it was a very deeply-entrenched habit of not speaking for fear of censure/criticism/mockery. I was impossible to get to know as a result, and it made me feel even MORE lonely and isolated. I consider myself as having suffered severe 'emotional concussions' throughout my childhood. These days, there's so much more awareness of the terrible repercussions of head injuries, and the recovery process is typically quite arduous. It's even more so with emotional wounds, but neuroplasticity is an amazing thing, and rerouting patterns/finding effective workarounds can be done. Of course it's not easy but this is about very small and incremental steps to change.
We were INDUCED to believe that we were useless, not worthy of love, and are habituated to feeling like total shite.This is an old, useless and pernicious identity, and one that needs to be outgrown. I found some very interesting stuff (not much that's recent) on something called DESNOS (disorders of extreme stress not otherwise specified). It's different from PTSD in that it's premised on protracted childhood trauma as a result of useless parenting. A key symptom is f*cked up interpersonal/relational dynamics.
It was a relief to realise there were valid reasons for how I behaved with human beings!