If I'm being completely honest, I dont really believe we have free will. Or we do, but in an almost entirely meaningless way on a civilizational scale. While you might be able to make small choices, material conditions and the flow of history ultimately decide the course of your life. We're all just products of our environment which none of us can change on our own, and as much as we can change our environment as a collective is decided upon by current conditions which are determined by oast conditions, etc. Basically i think the entirity of history was determined at the big bang, and were all just along for the ride.
So forgive me if I'm just not getting your point, but it reads like you're agreeing with me. I'm not religious or spiritual, so I don't believe in a self outside what is basically our brain (and by extension, our body). So your brain takes in the input of the world around, and then determines how you'll react. You can't control your brain (or as far as you can through medication, etc is determined whether you will or not by your brain, and the period you live in on whether you actually can). You also can't control the world and culture you're born into, so I don't see any room for free will.
I think we're pretty much on the same page 😊.
In a material world the concept of "free will" doesn't make much sense as like in your example, for "you" to be exerting over control your brain and body to get them to make "free will" decisions, the way "you" is defined has to be more than a brain and a body (which the brain is part of) and have a non-material spiritual/mystical component.
The "history was determined at the Big Bang" thing is a little trickier. The way things work at a quantum level almost certainly adds an element of true randomness to how the universe works, so even if you had perfect information about the state of the universe at the time of the Big Bang but couldn't perfectly predict how quantum states would collapse without collapsing them (which, by our experimentally verified current understanding isn't possible) you couldn't predict the history of the universe. That still doesn't add "free will" as doing so would just defer the role of the mystical "you" to manipulating quantum state collapses but it does bust determinism as a theory.