Is it Possible To "Imagine" Memories

This is going to sound insanely weird and this might be the wrong sub to ask, but I'm starting to freak myself out. I recently got this nagging thought in the back of my mind saying what if you're imagining your experiences or changing the narrative in your head by that I basically keep thinking if all of the memories I have of these girl bullying/ talking about me didn't happen or I made it worse than it was.. I know it sounds weird and I know I saw and heard these things with my own eyes, but I just wonder if maybe somehow I'm crazy and don't know it? This really sounds crazy. Sorry if this question doesn't belong here, I'm going to post to other subs as well. Any advice or experiences would be greatly appreciated