The question here is: what proves that you are what type you are? Or not?
I know I am not an INFP because...
1. I like arguing and conflict to the point where I can't have an intimate relationship without it. I routinely get into nasty conflicts with people at INTPc, in fact I seem to be one of the more aggressive Ts there. Speaking of which, 5 minutes at INFPgc makes me wanna barf. Agreeing with people bores me to the point of insecurity. If I agree with someone I feel absolutely no connection to them--I just feel like there is nothing to talk about.
2. I spent the vast majority of my life trying to reason myself to a philosophical endpoint. This was all about logic. It was not one iota about gut feelings or love or anything. The 22nd year of my life was like one big existential crisis. I simply refused to resolve it with anything other than logic and the pursuit of truth.
3. I had an INFP roommate for 4 years, and the difference between him and I was obvious. In a very similar way, we were both spiritual seekers, but his approach dealt more with what I mentioned above--feelings, love, etc. He has recently strayed over toward Christianity. I was the more vocal and analytical of the 2 of us about it. I would constantly find myself facing paradoxes and fighting tooth and nail to resolve them logically. Whenever we talked about our very similar struggle, though, I felt that it never went anywhere because he always agreed with everything I said, and I felt like I would be insulting him if I disagreed with what he said. ALSO, and Jack's going to hate this, it was easy to tell the difference between my inferior Fe and his inferior Te. The telltale signs were blatantly obvious. I got into major conflict with each and every roommate of mine on occasion, but the INFP did not. Rather, he simply could not fulfill his duties as a roommate. No matter how much we hinted, he never cleaned up after himself, never did anything unless he was told--at which point he'd do it. If I had been told, and sometimes I was, I would react violently. It insulted me to realize that people thought they needed to tell me what to do, and I made sure they knew there was conflict.
I'm a textbook INTP. If you doubt that, you need to reassess your personality-typing abilities.