I have not done attachment therapy and would not because I personally do not believe in it and think that the structure of therapy is far too limited for that sort of thing. I find it much easier to work on such issues in everyday relationships. It's good that some people have had success with that kind of therapy though.

One interesting thing about digging into past traumas that way though: there are some interesting research studies showing that it can actually be more damaging than helpful because it revives those memories over and over, consolidates them rather than helping to let go. This is some neuroscience work looking at the biological processes associated with it, not just based on anecdotes and self reports. One problem with what therapy does is that it only/mostly raises awareness without changing reactions and the way we deal with things in everyday life and this is probably part of the reason behind all those difficulties between sessions. Why I prefer to use help that is not so structured and can be accessible as needed. Not traumas, but I experienced this in relation to my struggles with addiction - no way I could have resolved that using therapy alone, these things are far too unpredictable for such organized, scheduled work.

I personally also don't believe that serious traumas can truly be healed (vanish as they never existed) - it is more that they become part of who we are and will influence our feelings, choices, behaviors in a persistent way. Same thing when it is said that a good T should have resolved all or most of their issues - what does that even mean? What I believe more is that we can eventually put a lid on them and leave them alone such that they won't have overwhelming power over everything, but that development hardly ever comes from talking alone, it comes from engaging and experience. I think that is better than constantly picking on the scabs (which mere repeated talking and analysis can achieve). In terms of relationships, I think it's better to learn to choose and maintain compatible ones at least for close personal relationships... e.g. for someone who is very independent, don't go with partners that always expect attention and care, or for someone who likes a lot of interaction and attention, probably better to chose ones that are interested and more generous and available. Also maybe better not to repeatedly engage with emotional opposites. I just can't see how a therapist could provide these things as feelings and normal human interaction don't come packed in a box that we only open once and week for an hour and then put in the corner until scheduled again.