Coming to terms sucks. I don't get headaches but I do get stomach aches and I too suffer from the dreams and memories of the "after effects" of CSA. But I don't remember anything from the original incident (if there even was one). The multiple CSA from my childhood and teenage years that followed I do remember.
And I remember most of the verbal and emotional abuse. Ironically, I still have been struggling to figure out why I am so messed up. Why, if I had such an amazing family and good, safe childhood I turned out like this.
I go back and forth - like you said - in waves.
Some days I look in the mirror and I can see everything bad that happened, know that everything wasn't perfect, but that I got through it. And now I just need to start working through the emotional bits.
Some days I look in the mirror and wonder why the hell I would be such an emotional wreck and burden on my family. Why I would sabotage so many opportunities. And why - when nothing ever even happened to me - that I would feel the need to "reach out for help" and "seek attention" and stupid things that I just wanted to fulfill whatever twisted idea I wanted.
A lot of days I avoid the mirror all together and toil with the thoughts all day long instead of doing my work or homework or anything productive like the laundry I really should be doing right now.
As for the dissociating, Im not sure if I really do that. I seem to remember everything (good or bad) in third person. I see things that happened but more as if I was a floating orb and not me because I can see me. I can see the whole scene. And of course, that's not what it looked like because Im not a floating orb. Sometimes talking about the abuse I need to start in third person as well. I don't know if these things count.
I don't have the answers. And I don't have any amazing words of wisdom. I just hope you know you are not alone here.