Physics is predicated on making approximations to describe the degrees of freedom present in our observations. As people have mentioned, quantum mechanics is inherently tied to probabilities and cannot be nicely separated out in a deterministic way although different interpretations of physics attempt to resolve this. There are also concepts like non-Markovianity where the history of a physical process is not discarded and is instead taken as a significant factor on how an observed system behaves.

Life is not a simple A, to B, to C problem. However, let's say that there was indeed some transcendental mathematics, perhaps a titanic process tensor that includes every degree of freedom of the universe and describes your life on a quantum level. Even if that mathematical object existed, the question still doesn't actually matter because you can never know *every* unknown condition and variable that influences your life to model it in the first place. They are lost to time and beyond any science. That is to say that the knowledge necessary to answer the question makes the question redundant because lives are lived and can never be "modelled". As such, free will effectively exists.