MBTI is a little addicting, though. It's like a mystery you have to solve. A puzzle. And I think that's cute. But it's frustrating and that ain't.
Haha, I'm pretty sure every teenager feels INFJ at some point. Everyone thinks about the future to some degree, writes about sad things, the works haha
But I see what you're saying. If you want to differentiate between, say, ENFP and INFJ (which have the same functions, just opposite each other), the ENFP could be simplified to - "I think positively about the worst." Whereas the INFJ could be said to think, "I think negatively about the best." Not exactly converse, but close enough.
If you've ever read that ENFPs are attracted to novelty, it's because they're trying to say 'novelty' in the true sense, where novelty is a concept, bold, new, refreshing, everything you think it is. That word could basically encapsulate the ENFP if you wanted it to.
And it's good you're changing more now, it's always good to grow and develop.
I too got a little frustrated when I learned you could have only one. Type, that is. (It could be a sensor thing, but also just my frustration. What if my type is sucky? What if I don't like it? Can I swap it out for something different? No? Okay. I guess that makes ethical sense. But still...)