Do you see fusion and integration as two different words to describe the same thing tribeofone? I'm unsure if fusion and integration, and merging in fact, are the same thing.
I used to use the words interchangeably, but Una+ just pointed out to that they actually describe two different phases in the integration process. This resonated with me, I think I am largely fused but not necessarily fully integrated. This means I have no more overt symptoms (switching, time loss, memory issues), but sometimes I still tap into thoughts, feelings and memories that I don't recognise. I just found an entire "memory box" (that's what I call them) full of things one of my alters got up to over the last year that was entirely news to me. I suppose this will keep happening for a while until everything is in its proper place.
I relate to what you say about feeling like you're losing yourself the more fused you become. As unaware hosts, our entire sense of self is based on NOT accepting alter's feelings and memories as our own. E.g. I am a hyper-moral person, a walking guilt trip, always put others ahead of me, etc. Some of my alters on the other hand can be selfish and downright (IMO) immoral. I now have to accept that this immorality is "me" too, but that means my self-image changes from what it used to be.
You sound like you are well set up for attempting fusion, if you so choose. I think empathy with your alters is key, and understanding that they carry pain so you don't have to is, too. It does make things easier in everyday life and it does save a lot of time if you don't have to have meetings about everything - in other ways, it makes things more complicated. DID systems are teams of highly specialised "experts" who practice a certain "division of labour". Fusion means that every part needs to be able to handle every situation, a bit like Lenin thought communism would work

This can be very daunting for some alters, especially littles. But it can be done (fusion, not sure about communism

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It shows an excessive tenderness for the world to remove contradiction from it and then to transfer the contradiction to reason, where it is allowed to remain unresolved.
G.F.W Hegel