I would urge caution in making the leap from theories about what did or did not happen in early childhood, to the idea that you must form an attachment with a therapist in order to explore or fix these issues. These "attachments" can cause a lot of damage.

I'd also suggest that your capacity for self-understanding might be greater than you think or have been given credit for, once armed with basic theoretical understanding. This book explains a lot:
https://www.amazon.com/Body-Keeps-Sc.../dp/0143127748

Not clear if you are talking about actual self harm, but I've heard self harm explained as a way to gain a sense of control and to decrease arousal in the face of overwhelming dysregulation, tension, or anxiety.