Reinin dichotomies only^2 get in the way if you are typing other people by limited observation. Then you can be easily led astray by normal variation in behavior and idiosyncrasy.
If you are confident on what side of dichotomy you are, based on large experience, that is good information for self typing.

"As far as IEI, I am pretty sure I'm not. I don't think I am decisive; I don't think I am positivist; I don't think I am asking."
-This sounds weak, though. Because that seams to go in to comparing non obvious features externally.

The parts of the post where you talked about actual behaviors and experiences did sound Si to me.