YOU SAID:

all i know is that i don't know

INTO JAPANESE

私が知っているのは私が知らないことだけです

BACK INTO ENGLISH

All I do not know is what I do not know

INTO JAPANESE

私が知らないのは私が知らないものです

BACK INTO ENGLISH

I do not know what I do not know

INTO JAPANESE

私は知らないことを知らない

BACK INTO ENGLISH

I do not know what I do not know