I agree with you about the fact God hasn't decided everything. There are several other examples in the bible. There is the example of Nineveh, a city God was going to destroy but chose not to because of their repentance. There is also the story of Jesus at the wedding and how he was not going to perform a miracle that day but his mother convinced him to. Finally, there are the words of Jesus himself who says:

Luke 11:5-13
“Suppose you have a friend, and you go to him at midnight and say, ‘Friend, lend me three loaves of bread; a friend of mine on a journey has come to me, and I have no food to offer him.’ And suppose the one inside answers, ‘Don’t bother me. The door is already locked, and my children and I are in bed. I can’t get up and give you anything.’ I tell you, even though he will not get up and give you the bread because of friendship, yet because of your shameless audacity he will surely get up and give you as much as you need.

“So I say to you: Ask and it will be given to you; seek and you will find; knock and the door will be opened to you. For everyone who asks receives; the one who seeks finds; and to the one who knocks, the door will be opened.