Over planning and scope creep are a problem, but let's not swing the pendulum to far the other way. Some of my most successful projects were projects where I planned out and worked through most of the features ahead of time through the process of modeling my data without any working software to try out. When I'm in that phase, I often don't really know what is too much. If I leave out features I think I or the users will probably want, I spend a lot of time with significant redesign of core aspects of the code. If I'm wrong, the project gets too big and we chalk it up to scope creep.
My ability to get this right is often a matter of how well I know the domain. If I don't know the domain as well I think I do, I fall into a lot of rework. If I know the domain more than I imagine then I waste my time with a baby step process when I could have run. All of this is a big judgement call, and I have "regrets" in both directions.
I think the ideal solution is to spend a lot of time in the analysis phase to load your brain up with the correct context, but then be ready to throw out the overengineered solution and just build what feels right.
Don't fall prey to sunk cost fallacy. Just because you spent hours researching a PhD level topic doesn't mean you now have to use it in your project, if it's not quite the right application.
You worry too much about being wrong. Just try something and adjust as needed.