Childhood trauma and coping

I was a selective mute til I was in 7th grade. Overwhelming social anxiety, abusive alcoholic parents, etc. Fast forward several decades, life is good, but I was still feeling like the trauma needed processed and spent 8 years in therapy.

The last few years with my therapist, I started writing with my non-dominant hand. I filled journals with conversations with younger parts of myself. There were some spiritual, very deep messages as well as memories of abuse of which I have no recall. Intertwined was their want to help me heal. My therapist told me she thought I had DID, which I didn’t want to accept at the time. The writing said that they went away when I became stronger and they were no longer needed.

This was several years ago that I stopped therapy. I haven’t looked at these journals or written in them for years and have just started transcribing them to hard copy. It is fascinating now to reread but I am wondering if she was right. However, she said I "have" DID while I would say there are no symptoms or signs of such since element school.

Basically, my question is, is it possible for a child with parts to heal and have them merge as one matures and finds other ways to cope?