So at this point I think it’s safe to say that Ponko did in fact used to be a war machine of some kind. I was surprised by the bouts of existential dread and depression mixed in with the other personalities, it would make sense if those were fears she had beneath the surface right now, but if each was a fragment of a whole segment of her life then that implies she went through some pretty dark periods of time between war bot and Chiaki nurse…
I kinda got the impression that those were corrupted versions of her previous personalities. There are a lot of goofy faces on page 107, and I kinda doubt they were all real. Also the "nyan nyan" one was extremely cute, but I don't think that was a previous personality.
I think it's more likely that her current memories and fragments of old ones combined into some sort of weird corrupted version of her, and each time she went in the freezer different bits of memory were mixed together. Maybe that "nyan nyan" one was because they are taking care of that cat?
Though it is possible that they were all real, and then you'd be right that she has been through a lot of horrible stuff. I guess we'll have to wait and see. I'm very excited to learn more.