i personally wouldnt call what i do age regressing, more like going back to coping mechanisms i used as a child like colouring or watching my favourite childhood shows or eating my favourite childhood food, because theyre familiar and comforting. sometimes at night when everyone else is asleep ill go downstairs and drink chocolate milk and eat biscuits while watching a show from my childhood and hugging my favourite stuffed toy in the dark just to feel like an innocent kid again.
i get what you mean about being embarrassed about it, i feel like i shouldnt do this and i should just act like an adult like everyone else does and expects me to, but as you said its just our brains trying to cope with trauma, its not our fault that we do this so we dont have to be embarrassed by it. if it helps us cope, thats the most important part.