I think what would help you the most is reading these 2 pages.
This will help you understand what each of these functions means, depending on its placement:
http://sociotype.com/socionics/functions/Ego/ (Click the other Ego & Id blocks as well. All 4 are important.)
And maybe read these to help see what it would mean if you flipped a letter: http://sociotype.com/socionics/types/ILI-INTp/ http://sociotype.com/socionics/types/LSI-ISTj/
As for my opinion... no. An ISTP wouldn't care enough to ask this question. Joking, joking! But really. They feel uncomfortable sharing things about themselves or talking about themselves a lot. They're very curious and interested in how things work but they can be seriously lacking motivation and not be very interested in identifying goals for themselves. This can make them both a blessing and a curse if you work with them. On the one hand, they almost never get mad at the people they work with (because they don't really care one way or another - they just want to leave soon so they can go back to video games). On the other hand, they aren't really interested in working. Yes, they're loyal to their ideals and they're going to help you out if your friends, but they don't really want to do any work. (This is a subjective opinion, of course, and it would be good to keep in mind that I'm pretty biased about physical work, being an Istj and all.)
However, the fact that your asking everyone what the answer is instead of investigating yourself makes me wonder if you're really an INTJ. INTJ don't usually ask everyone else for an answer unless they've already done a lot of research and haven't been able to intuit the answer for themselves. (I mean, they definitely like to ask questions, but not usually about something that can be discovered by research and by looking at yourself.) This is just an observation, though, and just asking a question doesn't mean anything definite about your personality.
I think something that would probably be an indicator of whether you're an SP or an NT would be how you work and how you get upset. If you easily place goals for yourself and usually feel extremely driven to do those goals, you're likely an NTJ or at least an STJ. It might help to remember that ISTJs can endure extreme physical labor and INTJs can endure extreme mental labor - while both types can do either of these things, I believe they're more prone to the ones I just stated (because of their demonstrative functions). Consider how you get upset. If you get upset because someone is interfering with the environment, you're probably an SP. If you have a hard time getting upset because anger scares the crap out of you, you may be an INTJ. The INTJs vulnerable function is Se. In other words, they don't understand physical and territorial stuff. I know an INTJ. He freaks out if you poke him. (I'm the only person other than his family who's even allowed to hug him.) He sees poking and tickling as some kind of aggression. He's also the only person I know who can seriously let his leg or arm fall asleep because he's in an uncomfortable position and not even notice it till he moves. :/ As a sensing type, I don't understand how it's possible to not notice when your body is telling you that it's uncomfortable or that you need to move before your leg dies. I work with an ISTP. He's hard to dislike, he doesn't pass judgement on people all the time (or doesn't share the judgement, if he makes one), he listens well. He's an S, but he doesn't make a big issue of being a guy. That's important. Many male Sensors take their masculinity way to seriously. ISTPs aren't like that because Se is their ignoring function (sociotype.com/socionics/types/SLI-ISTp/) so they understand power very well, but tend to be completely disinterested in their power or anyone elses. An INTJ simply doesn't understand power hierarchies. They want things to be done right and often feel that they know how to do it correctly, but tend to have difficulty making people "follow their lead" because they don't understand Se.
Hope the links or opinion helped.