My memory for things that have happened to me in the past is pitiful. Almost scary how pitiful. I sat across the table from my mother who made a comment about seeing a musical for the third time and how it wasn't as good as the first time, but better than the second. The second time when I bought them the tickets as an anniversary gift and accompanied them with my then husband. I still don't remember the event. And if I didn't know how well she remembered events I'd think she was making it up.
I do remember important (to me) times / events / feelings, but the smaller things fall by the wayside and always have. I do treasure those memories I've kept.
I also keep a journal / blog / diary (several actually, for different reasons) and when I go back and read entries I'm often amazed to find how much I'd forgotten.