Hello Kimani, thanks for this thread. Your bolded text is what I was afraid of and led me to start this thread:
http://intpforum.com/showthread.php?t=18265. As a brief summary of the exchanges thereon, I consistently have scores like the following even when professionally tested. I am always right at the border of INTP and INFP in my scores. The one below has a 2% spread, often it is even or just one (the one almost always favouring INTP). As I also stated, and as others confirmed, when I read various profiles on INFP and INTP and show them to others, we agree that 75% or more of both apply equally to me. So, if this suggests mental illness or disorder, do you know what kind? My scores on your test were 29/22/18 = designer I believe (but don't get the hero versus old man part). I work in one of the fields you have listed for designer and have wondered, more so in my adult life, whether I have a mild form of Asperger's.
http://www.25quiz.com/
19% INTP
17% INFP
13% INTJ
11% INFJ
11% ISTP