The problem isn't your thinking. You have plenty of that.
The problem is there's no process. No workflow that takes a decision from “I'm thinking about it” to “it's decided.”
So decisions just live in your head. You reconsider them every time you think about them. They never resolve.
Engineers know this pattern. Code that never ships usually isn't broken code. It's code with no release process.
Hard decisions work the same way. Past a certain point, more thinking isn't rigor. It's the absence of a process that knows how to close.
The fix isn't to think less. The fix is to design the decision, the way you'd design a small product.