Not remembering key details of a traumatic event is more common than one may think. In my case, it started with the first time I had sex, but I shoved it away because there was no way that had happened to me. Eventually, one drunken night I had a severe flashback and dissociated the rest of the night and into the next day. I still didn't have the full memory, I mostly just felt the physical pains/sensations. It was only through working with a trauma counselor that I was able to access more aspects of the event, though I'm still missing a piece or two. That was one memory but I have recently started having flashbacks, dreams and intrusive memories (if that's what they are) over several different events. I'm unsure if this really took place, though my counselor is pretty sure these are memories because of the trauma work we've done.

Long story short, I believe the only way to truly know is through therapy. In my case, my counselor did something called brainspotting. It's like EMDR without the being re-traumatized. It helped me a lot and I'm still using it to work through these "new" memories. Take care and PM me anytime.