Assuming you're an IN, the most unreliable thing about the official MBTI, in my experience, is that it's not uncommon for INFs (at least if the F preference is mild) to come out INT, and here's some recycled reckful on that subject:
Originally Posted by reckful
In four years of participating in type-me threads at INTJforum, I've often noted that I think it's not uncommon for INFs to test as INTs, at least partly because many of the F choices on typical MBTI tests (including the official test) are choices that are more likely to appeal to SFs and EFs than INFs — and not only do I think that's more true of INFJs than INFPs, I think it's probably even more true of female INFJs than male INFJs. I think male F's are often aware that they differ from cultural male stereotypes in ways that make them more "F-ish" than average whereas, by contrast, I think INFJ women who compare themselves to cultural female stereotypes (not to mention the majority of actual women) are reasonably likely to think of themselves as more T-ish than those "feeler" women (EFs, SFs and, especially, ESFs). In any case, it's certainly been my experience that it's considerably more common for an INFJ (male or female) to mistype as INTJ (and later conclude they're really INFJ) than vice versa. I think that, in some ways, it's fair to say that INFJs are both the "least F" of the F's and the "least NF" of the NFs.
So... if you end up with relatively clear INTJ results, I'd say that means you're probably an INJ, but may or may not be a T.
In case they're useful to you, I've put online profile roundups for the four IN types in the spoiler.