1) I know I am an extrovert because I gain energy from interacting with people. I like to be alone a lot (the vast majority of the time in fact) but it makes me become extremely low energy, and I feel much better and more alive just by walking out the front door after a long period of isolation. I am the kind of person that is very reluctant to go to parties but in the end never wants to leave. I also find it hard to sleep when it is light, the dark makes me tired (and this has a very strong effect, I think stronger than in most people). I also have a hard time getting to sleep if I know somewhere out there something important or fun is happening and a lot of people are involved. I get fear of missing out big time, and I kind of have to tell myself that there is no reason to feel that way because a) it's not as great as I think it will be b) this will happen again soon (usually - I had to go check out the bars on halloween and it was crazy even though I had a 630 am training session the next day). I am an International Relations major and because of this I have a hard time sleeping when something big is going on somewhere in the world, its just exciting to me...and I am comforted by the fact that people are always awake and doing something somewhere. Closed up streets with no people on them depresses me.
2) Well all the things listed above definitely make me different from an introvert, although I assume a lot of people who are not familiar with the proper definition of the word would consider me one. My writing style is very introverted and unless I know someone extremely well I am a person of few words, I prefer not to say hi to random people on the street. I take some time to get adjusted to social gatherings and seem awkward at first, particularly if there are people I don't know there or who don't "fit" with me well, and I have a small but close circle of friends rather than a ton of them. I wear an introvert mask for sure, but I am definitely not one. I am more shy than an introvert and I HATE small talk unless I am drunk.
3)Heres the thing, I always considered myself a strong thinker, it was the only thing I was sure of in my type. Before this I would have typed myself xxtx. Which doesn't make the T look super strong but it was the only one I could put down for sure. Now I realize I am more of an exxx. I always go with the rational and logical decision in the end and I feel very bad if I don't. I force myself not to consider my emotions because I know it is irrational and ultimately not what is best even though I really want to listen to them sometimes. This makes me think I repress my feelings rather than being a true thinker, and this is what the person on PerC told me as well. It's also been suggested that my Fi and Ti are very even and that because of that I can't actually differentiate them. I don't know if that is true. I certainly believe that it is illogical to not treat human beings as emotional beings because they are, so always making a decision based on cold hard logic is not always, in fact, the logical thing to do...but this attitude seems more T than F in origin.
4) I don't know if I am a sensor I think my N and S are pretty equally balanced. I've always loved sports though and I seek pleasure through physical sensations (drugs but not anymore) which seems pretty sensorish to me. In addition I take things very literally. I was listening to a song where someone was talking about having a "range rover all wood" and I said "a wooden car...that doesn't seem very practical" I didn't realize that the rapper meant the inside of the car until someone told me. I'm also very aware of my surroundings and notice things other people do not, but I also use them to connect dots and come to conclusions (so that is more of an intuitive thing I think). I also loved playing sports when I was younger and am a fast hands on learner.