Selective Amnesia

My supervisor says that a person can have selective amnesia. I think it's kinda true, I think it may just be happening to me. Maybe it's the many things going on all at the same time and I am using too little of my brain. Can a person genuinely forget something that happens to them at some point in their lives? Perhaps so. If our mind can have a limited storage space like that of our memory card then it can't possibly store everything.