Hi Adelissa! Well, you know, we really can't diagnose here, so...I'll go to the other stuff.
I wouldn't make too big a connection on the Lamictal... lots of things are used off-label (another good example is anti-psychotics... it doesn't necessarily mean someone has psychosis, it's just that it's something that might work). In fact, my BF also goes to my psych, and she has mentioned the possibility of trying mood stabilizers, and he has depression, not bipolar.
Onto the Myers-Briggs! I was rather into this a number of years ago, finding it quite interesting. As far as the fit goes for that, I'd be an INFJ. I used to think it was a P, then when I had a lot of up in the air things that couldn't be settled for a considerable time, I got very anxious about it, and didn't like it
at all. Which made me realize that I really hadn't had a very accurate insight into myself on that (which of course is one of the limitations of its accuracy).(Since then, a T that I knew just as an aquaintence, not professionally, was talking about Ennaegrams(sp?), and I found that a frighteningly close fitting system, far more --for me-- that MB.) Anyway! (Lol, I digress a lot too!

) I very much relate to what you say about the Myers-Briggs,
in that I seem constitutionally incapable of answering so many questions w/o disclaimers. Especially, as is your experience, on the I/E scale. You also have a rather indistinct S/N. No worries, lol, balance is nice!

(I've seen too where they designate even splits with an X.) You show a good understanding of MB in pointing out that it is a
preponderance of tendencies, not absolutes, which does seem to confuse a lot of people.
I
don't think any meaningful connection can be made between MB and BP. Interesting that you find a stong need for labels. I kind of have to laugh, because it's familiar in that...at the same time I'm a total sucker for personality questionnaires, I'm sooo not a box-able person nor do I want to be(!) Lol. Just hopelessly curious what people come up with on a fascinating topic I guess(!) I
completely relate to what you say about knowing that somehow, at some level, you're not alone in this and that there are others who understand. Which is why PC is so great!