Just for what it's worth,
@CindyLou, I don't have any view on if you're S or N (I'm very happy to back-and-forth with you based on how you see yourself), but for overall information, Jung's view of S-N was
quite different from the one measured by the MBTI test -- for instance, to him, the archetypal scientist is a sensation/thinking type, because sensation was one's connection to the tangible world. Sensation-thinking is supposed to be classically empirical, whereas Intuitive-thinking is more speculative.
I could see a lot of NT types in the MBTI test's framework (which is more Big 5-ish than Jungian) being what Jung would call sensation+thinking types. The reason is that N in the MBTI is more related to Big 5 Openness: it's possible to be unconventional, prefer theories to facts/figures, like discovering the new over the old (they could be
new sensations, not
new intuitions) while being what Jung would call a sensation-thinking type.
The view that Si has to do with comparing with the past is standard in Berens/Nardi stuff (seeing how things were vs how they are, and so on), but really in Jungian systems, Si was simply the subjective perspective on sensation. I mean, philosophically here's how I think of it: sensation tells you stuff about external objects you can interact with, but from another perspective, sensations are something only you can access: nobody else knows how you see a strawberry's redness but yourself. When you present a logical description of its properties it's abstracted away from your experience. But the fact is sensation has an
experiential component, which is deeply subjective. I personally think the views that say it has to be past-oriented are mistaken; there's no reason Si can't be as present-oriented as Se, apart from the fact that it's true your subjective impressions of a sensation do build upon past experiences. But frankly, that's true of every function: what logical connections you draw often are dependent on what you've done before -- that's how humans
learn!!
I don't see why remembering prior logical facts you've learned has to be Si, it can just be part of Te or whatever.
Regarding Si being mistaken as intuitive: in general, my view is that all irrational functions are what we would call
intuitive. That is, they're more impressionistic than coherent judgments. They tell us how things appear, before we then decide to characterize them more precisely (which can involve choosing an axiomatic framework and other peculiarities, or a cultural framework to value-judge, or whatever.) They consist of the basic raw material out of which we synthesize our knowledge. I think the thing is just that our impressionistic knowledge is sourced both in how our mind fundamentally creates schemata with which to build ideas and from data that arises from the tangible world.
When we see a ball roll down an inclined plane, that is an impressionistic intuition which can then be logically abstracted into equations about friction, etc. The mystery that the math works to describe the physical world is sort of the difference between sensation and logic.
Usually the difference is that intuitive types seem to focus more on possible such schemata, vs the sensation types (again, from my interpretation of a functions-y point of view) can be equally curious for new ideas, but for ones sourced more directly in reality.
The latter can secondarily employ the former, but the question is somehow on the focus.
and @Sriracha doesn't count because she's an honorary infj
I like ambivert too. I can't be pinned down! 
