The short answer
No. There is no good evidence that he ever wrote anything down. The Analects is five hundred and twelve short passages, assembled by other people over generations after he died. He does not speak in about a hundred of them.
Some parts are not even trying to be his words. Book 10 describes him from the outside, as a set of habits. Book 19 is his students' sayings and quotes him only at second hand. Book 18 treats him as a character in anecdotes, several of which he loses.
How old is it?
The earliest copies dug out of the ground come from Han dynasty tombs of the first century BC: Dingzhou, sealed in 55 BC; a tomb at Pyongyang, 62 to 45 BC; and the Haihun tomb, 59 BC. People begin citing the text as a book only in the late second century BC. That is three centuries and more after his death.
The life story was fixed before the book was. In the Haihun tomb, beside the bamboo strips, was a lacquered mirror-stand carrying a short life of Confucius with his height on it.
So can we trust any of it?
Scholars have argued for a long time over which layers are early and which are late. One school holds that only part of Book 4 preserves anything like his voice. Most specialists reject that particular scheme, but few now defend the old account that his own students compiled the book.
The honest position is the one the book takes. Every quotation from him is a quotation from a compiled text of uncertain date. The most that can be claimed for any of them is that a school which revered him believed he had said it, within a few generations of his death.