What you are describing (not being sure about your memory) reminds me most of dissociation, which is normal to a certain extent as everybody dissociates at times. Whether or not your experiences are normal depends on what impact it has on your life, or how much it bothers you. Since you are here asking about it, most likely this does bother you. You might want to talk to a professional about it either to put your mind at ease or to see if they do recommend treatment for you.

I think that you would find some things that you relate to, and some explanations, in the book, "The Stranger in the Mirror" by Marlene Steinberg. http://www.strangerinthemirror.com/ She discusses dissociative symptoms, with explanations for them and to what extent each type of symptom is normal.

Rap