I have taken the smaller sample type versions on Facebook, and once got an INFJ and another time I got INTP. I understand the J since when I took the full version it was my weakest. I still know for sure that I'm a P though.
I'm an INFJ, but sometimes type as an INTJ. I think as I've gotten older that I've learned to be more of a thinker. It really started happening in high school, when I first became interested in school, and has continued through college. However, I am definitely an F, even if it's my weakest letter.
I used to mistype as INFP a lot. Now I mistype as INTP more often(see signature below) xD
I actually could be an ENTP, but I'm certainly not an INP as my Ne is very strong and is most definitely my dominant function. Plus, INPs use their Ne very differently than ENPs do. By that, I know that I'm not an introvert.
I mistyped as ENTP a couple times, ENFP once. I know I'm INFP though, the other descriptions don't fit me at all. Although my I isn't very strong and I've developed my T pretty well so I confuse myself sometimes, but I always fall back and INFP never fails to explain me.
I've never typed as anything different, but F has typically been my weakest preference. I've found over the years, that my inferior Te is more developed, so the closest I've been to testing as another type is INTP.
Since the very first time I ever took a MBTI test, I've never got anything other than INFP.
But I'm not a very strong I, and I'm sometimes not unlike ENFPs when I'm feeling more extroverted.
Since I study/work in the academic field, I've also had to develop my T side: I've learnt to ignore my F-ness for short periods of time, while I'm working on an assignment, for example.