Look further than the P/J thing itself. Types are more complex than that. I sometimes test J, but it is so obvious that I fit the INTP description so much better. Test results are nothing more than a starting point...
My view is that your both. People don't come sorted out into types.
The way MBTI works is that it picks 4 qualities, separates them into poles, and makes predictions based on people who are polarized (strong Js, strongs Ts, etc.) in their functions. Does this mean that people must be polarized? Absolutely not, but the theory and predictions works best that way. The biggest mistake that people make is thinking that reality (your personality) conforms to this descriptive system.
Think of it in terms of politics. People just have opinions and they're all over the place. We can look at something like attitude towards big business and begin to sort people out into two camps: mostly support, or mostly condemn. We'll call the supporters republicans and the condemers democrats. But lets say you're not 100% how you feel about big business. Your views vary with the type of business, the purpose, the conduct, etc, so you're not sure whether you can be classified as a republican or democrat, and you get stuck. Kind of absurd, ain't it?