mmm16, I am so sorry you had to go through that. I understand what it is like knowing that something happened but not knowing what. I was 5 when it happened to me. I always remembered the first part but not the actual rape until 42 years later. I am still recovering memories. I remember trying to push past the wall, there was one point that I could never get past. It wasn't until after my divorce and after my grown children had all moved out on their own before the memories came back. I don't think I could have handled the memories before then even though it still haunted me. There were other things too that helped to trigger the memories, just life circumstances that mimicked part of the attack.
I agree with rainbow and cherryblossom, the exam may not show any evidence. I hope that there is none, but that still doesn't mean that it did not happen. Having someone to talk to can help you process what your nightmares and flashbacks are all about and if it does or does not indicate what you suspect happened. It is important that who ever you talk to does not push you into one direction without allowing the memories come back on their own.
If your memories are starting to come back it will help having someone to talk to and give you some support. At least have numbers to call. When my memories came back it was a flood of memory and emotion and can be overwhelming. A part of me knew it happened many years ago but another part felt like it just happened. It took many months before I could talk and write about it in the past tense.
Please be kind to yourself, as hard as it is to do, try not to worry about the exam. The medical staff doing the exam have seen it all. They will be professional and will give you the facts. If at all possible, can you take someone with you for support?