It's supposed to take effort to find your type. Jung actually diagnosed people, one on one, in his office. The more reading and study I've done, the more I trust the opinions of people who have also read and studied the cognitive functions vs. people in general, or silly Internet quizzes.
See...if you're going to go by Keirsey...you're going to embrace a very simplified version of type. But it has little to nothing to do with Jungian type theory. Like really, Keirsey didn't get it. You CANNOT be INFx or ESTx. It's impossible and improbable. There is no borderline Judging and Perceiving. There is the dom function, the generic manifestation of that dom function (T or F, for example) then the conflicting inferior. J/P is determined by that dom function.
And it's okay to keep questioning it the more you understand function theory. I don't think I FULLY got the difference between Se and Ne until last night, when an INFP (actually 2) showed me the difference in their perception of something as simple as a photograph.
Some people only know for sure their judging functions (like yes! I'm Te/Fi or Fe/Ti) or that they are an absolute introvert or extrovert.
Neuroses of the inferior come into play strongly in the Jungian function theory, and sometimes people have so many misconceptions that they don't understand that they are what they are.
Like me:
I thought I was an introvert because I don't ALWAYS want to be around people. But I'm very expressive. And what is more, I'm easily bored. If I have to wait, I HAVE to engage with the outer world in some way, I stand up in restaurants to look at pictures on the wall, grab meaningless pamphlets to read...it's ridiculous how extroverted I am, and I didn't even realize it, because I thought that meant I had to be some super needy person who wanted to be around a bunch of people ALWAYS. Or that I had to LOVE ALL PEOPLE. I can barely sit still. I have to get up and walk around. I do two or three things at once if I'm not sleepy or tired. I want to be engaged with the world.
Also, I thought since I'm SMRT and like BOOKS and ANALYZING STUFF I HAD TO BE AN N.
But I really think I'm an xSFP now, like really really, like whoa why didn't I realize this sooner.
Yet it was because of my own lack of understanding, that's all.