Thus hypothesising an original integrated self? I think Gurdjieff used to promote the idea that the self was never an original unity - only something to be achieved.
Like you, I've done what seemed like a fair amount of reassemblage during my life.
The expert on this in Jungian circles was Michael Forham, who I think posited an initial state of infant with mother, involving blissful unity, feeding at the breast, having one's needs met, being loved and held. However, as we all know, this can rapidly break down into feelings of chaos, fear, anger, and so on, or in fact, never got going because of parental failure. This is a kind of deintegration, which involves loss, yet is also necessary, if eventually you are to become separate. In fact, separation and intimacy are twin poles here, and obviously we need both. But some people get too much deintegration, and cannot function properly. Of course, some people have suggested that the early bliss is the source of religious feelings, loss of boundaries, and even the notion of God. Who knows.