I've been typed as INFP on online tests, but when I took the actual one on paper, it came out as ISFP. Other tests have give me an ISTP as well as ENFP. Is there some kind of questionnaire which could help me determine my type?
Just kidding, it may help if you research the 8 functions separately to determine which ones you use most strongly. In INFPs this is Fi, so you may be very connected to your emotions and stand up for your strong views on something. You might take an interest in spirtualism, meditation. Do you have objects that you have a deep emotional connection with? Is your room full of these things, is it well decorated, do you have an atypical taste in music compared to others your age?