Q. Do you think our lives were determined by God the day we were born? Is it a fixed destiny regardless of the twists and turns? Or is changes from time to time?
I think the discussion in this earlier post will largely address your concern:
That post responds to a question asked from the perspective of God, rather than from the perspective of human experience, as your question is but the answer is really the same either way. As I say in that post, God is not the only free moral agent in existence, but God is able to work through the free choices, both good and bad, of human moral agents to accomplish His purposes.
So I would say that our lives are not determined the day we are born; God has built a beautiful but terrible freedom into the moral universe that allows us to make choices by which we might bring joy and blessing to ourselves and to others, or by which we might cause great suffering. But God hasn’t left us alone to make those choices and to deal with their consequences; rather, God is an active free moral agent right in the mix, and with His infinite wisdom and power, He is constantly at work to help us make our choices work out, if we will live in fellowship with Him and depend on Him. So we should pray for wisdom and strive to develop godly character, so that we can cooperate with God in his plans for the created universe.
As I say at the end of that post, I picture God out there saying, “Let’s see what happens next. I’m sure I can do something with it.” We should respond, “Please do, and let me know how I can help!”