Per Merriam-Webster, the definition of overthink is to think too much about something, to put too much time into thinking about or analyzing something in a way that is more harmful than helpful. Yes. That would be what I do sometimes.
I don't think I overthink things in general. Peggy might disagree. But there are times when I spend hours worrying about something and when I just sit down and do it it takes me minutes to fix.  It drives me nuts.
My current example is the kitchen towels I'm working on. This pattern started out as a scarf pattern in Handwoven magazine. I was taken with the idea of doing pinwheels in a plaid. I love pinwheels but in a plaid? How cool is that? So I changed the yarn, the colors, the size, the pattern and ultimate use of the weaving so I could make kitchen towels.
First step - I got all the warp loaded on the warp beam.  Next step is to thread the heddles.  I always start threading the heddles in the middle of the loom since I have a center divide in each heddle frame.  But some time passed and I was absolutely certain I wouldn't be able to figure out where I was in the pattern.  I have worried about this for weeks now.  Mostly laying in bed at night.
I sat down one recent afternoon to thread the heddles. I was so sure it would be a disaster. Can you guess what happened? Of course, you can. It took me about a minute and a half to figure out where I was in the pattern. Then I spent another couple of minutes double checking to be sure I was right.  Yup.  Hours and hours of worrying and a grand total of less than 4 minutes to figure it out.
My daughter is also an occasional overthinker.  I'm sure she got that from me.  I am so sorry to have passed that on.