"only knowing that" is correct and usable in written English.
You can use it to express that you were aware of only one piece of information or fact. For example, "I went into the situation with only knowing that I had to make a speech, so I was nervous."
I'd read and memorized and went in for the tape only knowing that Sally-Ann was a "non-white young female from a small Kentucky town who has a fascination with the Farrell's".
And the surgery would take years and she knew that she would likely never know the outcome, only knowing that I knew that it had been her decision to put me through the pain.
We begin to appreciate that Socratic epistemological modesty of only knowing that we don't know anything.
I was like this at their age: I remember falling in love with Wham!'s Freedom when I was six, without understanding it, only knowing that the bit that went "you know that I'll forgive you/just this once, twice, forever" put butterflies in my tummy.
But few Englishmen, only knowing that the Anti-Slavery candidate for the Presidency has at last triumphed, would be prepared to hear what his views really are.
Therefore, for convenience, we examined the large and small lagoon samples only, knowing that the medium sized lagoon samples were an intermediate situation.
They are not perfect, and sometimes create symmetry where there is none, but knowing that would only make the candidates more circumspect in their assertions.
Not only that, but knowing that if he missed his first serve he could be in trouble, Murray took some of the pace off his first serve and then Federer could attack that, too.
These websites may not make you scream, but they may certainly fill you with the sense of dread that only comes with knowing that sometimes reality is indeed scarier and stranger than fiction.
But the locals took to calling it "Osama's Mosque," knowing that only Gulf money could have afford so large a structure.
But the locals took to calling it "Osama's Mosque", knowing that only Gulf money could have afforded so large a structure.
