Not standing up for JA at all, because her story is self-serving and doesn't ring true, but my PTSD did involve amnesia of the worst parts of the incident for a few years. I did remember bits and pieces of the whole thing, but it wasn't at all like JA said. I was drugged, so clearly that makes a difference, too.
The two worst parts of the night I didn't rememer until after years of flashbacks that made no sense. I would lose it and not know why I was losing it. For example, one thing that set me off was seeing my psychopath's face late at night after the incident (we were roommates; she set up the rape and said something to me right before it). I couldn't take her face and had freakouts in my room alone or with my boyfriend. I thought I was going crazy.
I really could not remember what I remembered later (the two big things). My mind wouldn't let me until I was ready. It sounds silly, but it was like the last episode of MASH if anyone remembers Hawkeye's story.
So anyway, yes to amnesia, sometimes (imho, lol). No to JA's idiotic, self-serving version of it.