Do you have a therapist and have you discussed these pieces of memories with them? I don't think the pieces are going to let you "go" until you do process them, see where they lead, what they are about.

One comfort I have noticed for myself; usually one only remembers what one can deal with at the time so when/if you do remember the whole thing, you will be able to deal with it at that time. I'm not saying it will be easy to deal with, just possible.

Rather than try to "force" yourself to remember the whole thing, I would just go with what you have, maybe write stories with a piece, do multiple beginnings/endings? Just jog your memory a little at a time, gently, and without expectations. Accept whatever you have rather than fighting it, it is a bit like a dream, not actually happening in reality now. Whatever it is, the whole experience is with you and part of you so not something to be afraid of.