I have a hard time telling which one I am.
I frequently test as an XNTP, with a high perceiving element, but I'm starting to wonder if I'm leaning towards the INTJ direction.
When I first took the MBTI in 10th grade, I tested as an ENTP, and this made oodles of sense. My heroes were already Richard Feynman and other scientists, and I was a brilliant improvisational public speaker (but a failed school politician), I was horny and witty and programming and game playing and all over the place. Superlatives used to describe me included "quirky", "creative", and "smart kid but bad student". The years before that, I could imagine
Some incidents in my life have caused me to look at it more seriously. This year, I'm taking the IB (International Baccalaureate, for those of you who don't know. It's the closest to hell a high schooler can get to), and now it's becoming less and less viable for me to go on an improvisational spree that I was so good at before. Now it feels like I forgot how to ride a bike. The teachers are a bit more strict so voicing off my ideas is less plausible; it's all about analysis. I'm good at analysis, but I've always learned best when I debated and percolated in my head. But now I find it hard to talk to people, and I've lost the enthusiasm that is so signature of the ENTP, and the creativity that accompanied it. I've lost confidence in my ability to talk to people that I feel like I've earned. My girlfriend left me; my mum has breast cancer, so now my family is kind of hard to talk to. It kind of shook my roots.
Now I'm really sarcastic and not giving a damn, when a part of me wishes I was a bit more considerate. I'm very serious, very emotionally neutral and hard to excite. I've been directing a lot of insults at my sister, and I've been very critical of a bunch of stuff. I've been making future plans. It's all very INTJ.
An INTJ to me sounds like a quiet ENTP who schemes. If that's what I am or becoming, then great, but I'd like to have some peace of mind.