Does anyone ever feel developmentally stunted, as if you're forever stuck with the depth of a small child?

I had problems with hyper sensitivity, shame, and false perceptions/self consciousness by the time I was barely out of diapers (I think it's unusual I can remember that far back but oh well) and growing up I never felt like I had "a self" or perhaps was just too uncomfortable/insecure to form one. I hated being a kid and I hated it when people expected me to misbehave like most other kids at that age. It was hell being this neurotic and sensitive, and I internalized ALL of it. I could never relate to anyone.

I'm nearly 20 now and still, the only clear differences I can see between myself and my 2-6 year old self are more mature thought processes and not nearly as much random shame, which is to say I don't feel much has changed since I was born. I still feel like an unformed lump of clay and I don't even attempt relationships. With my high school friends (all have moved on by now) I would sort of compensate by mirroring them or acting a certain way around them that wasn't real.

It's like I was born wired wrong, and years of hidden negative reactivity crippled me. There was no way at the age of 12 (my first true breakdown) that they would recognize it as borderline pd, but 7 years later I feel just as empty and soulless, but much more tired and burned out from it all. I don't even have the diagnosis because they think it's a mood disorder due to poor communication, but it's only a small part.

Maybe I was never a child to begin with? I know I was never a teenager. It's especially odd for me feeling like a kid who has yet to become their own person while also being told and feeling as if I have an "old soul."