I have a similar situation as well. I know for certain that there were some incidents when I was under the age of 5, but have no memory of them. My sister was there and remembers everything. I remember his house, truck, him and even letting something slip that clued my parents in to what was happening, but no memory of the abuse.

I, personally, have decided to go ahead and deal with the trauma I do remember most of and not make the effort to remember the other incidents. It is a personal decision. If I started having flashbacks, I may make some effort to find the memory. I would be concerned about my mind filling in the blanks and not knowing if it were actually real.