You are not.

Your brain works like Bayesian statistics. It predicts what will come next based on previous connections made by previous stimuli. This is how neural networks "decode" information.

Westworld uses a perfect visualization for this when one of the robots sees their own code, and the words she's saying are being chosen based on a predictive model in real time. IMO, it's one of the greatest scenes in fiction history.

Free will is a philosophical question that has pretty much been entirely answered by science. Physics only suggests it doesn't exist, but neuroscience and logic demand it doesn't.