I believe you're cautioning that maybe what I'm noticing are sensory patterns my mind attaches to the thoughts after the fact, when I go in and try to analyze them, rather than the thoughts themselves. I actually had a few false starts this way, but later on I found what I think are my internal representations of the structure of logical reasoning. They are like fundamental thought-widgets (visual and physical, àla Einstein's claim) that fit together with a certain set of rules to form meaning. These could be after-the-fact sensory patterns as well, but since they are mostly visual I've started using them to create a picture-only language as a sort of proof-of-concept. I'll share more as it develops.

Also, I try not to think in words. Habitual word thinkers and non-word thinkers will probably have very different reactions to what I've been writing.

I grant that I might just have a particularly strong case of synesthesia. Hopefully the tank will bring answers.