Memory is associative. I have a really, really good memory, but it's mostly because I know how to exploit that associativity.
If you asked me what I did for the last two weeks, I'd have to find "anchor" memories to relate to other memories. E.g., I remember a conversation at work on Friday, which I know was the result of a thing I did earlier that day, which I had talked about doing on Thursday, etc. I can reconstruct things, but part of that is "digging" through memories to find anchor points.