Question about Freud’s “Psyche ist ausgedehnt” in Derrida and Nancy

In On Touching Derrida makes much of Freud’s posthumous fragment “Psyche ist ausgedehnt; weiss nichts davon”, and the fragment is also treated in Nancy’s Corpus. As far as I can see, the translation is always given as something approximating “Psyche is extended; it knows nothing of it.”

My question is this: how do we know that the final verb is a third and not first person singular? What is there to stop us translating the fragment as “Psyche is extended; I don’t know anything about this”? In other words, how do we know the elided pronoun is “sie” and not “ich”? The verb form would be the same in both cases [ich weiss nichts davon/sie weiss nichts davon].

It seems scarcely less self-contradictory to translate the verb in the first person than to keep the usual translation which claims to know what psyche does not know and, what is more, that psyche does not know it. Given the truncated form of the fragment it would seem quite reasonable to assume Freud to be saying that he does not know anything more about the psyche’s extension than he has stated in this brief phrase, rather than claiming not to know anything about it at all (which would make the two parts of the fragment contradict one another). I’m not convinced that it is simply enough to say that the usual translation “makes more sense”, and I’m not sure that the argument from self-contradiction pushes us more in one direction than the other.

It just seems surprising if this alternative meaning has not even been considered, however briefly, regardless of whether or not it is eventually dismissed.

There may be a simple answer to this, and I may have missed Nancy and/or Derrida addressing it somewhere–it’s a while since I went through On Touching. If anyone has a response I’d be grateful to know.