I keep getting INFJ and INFP on different tests. How do I tell which one I actually am?

You will not resolve this by taking another questionnaire, and it is worth understanding why before you take a fifth one. The INFJ and INFP descriptions differ on exactly one axis — whether your first move in a decision is outward to how people are doing, or inward to what you believe is right. Both codes describe someone who feels deeply, keeps it private, and cares about integrity. So every item that would separate them has to ask you to observe your own first move, from the inside, in retrospect. That is the least reliable observation a person can make about themselves, which is why your answer moves between takes: you are not measuring an unstable trait, you are measuring an unstable instrument.

The part that is stable is the margin. If you take a dichotomy scale and the T–F axis comes out at 52 or 47, that is a genuine finding — it says you sit near the middle of that axis, which is where most people are and which the four-letter framework has no way to report. A code cuts a single-peaked distribution down the middle and then hands you a letter as though it were a category. Two items answered differently on a different day flips it. That is the whole mechanism behind your two years of going in circles.

What can move the question is behaviour, because behaviour does not consult the description before it happens. The check that matters here is whether your decisions track a private standard even when the room wants something else, or whether they bend to the room and get rationalised as a value afterwards. You cannot ask yourself that; you can only watch what you do. A timed task with something at stake gives you one small instance of it — not a verdict, but the first piece of evidence in this argument that did not come from your own introspection.

A more useful framing: stop asking which code is correct and ask what you wanted the code for. Almost always it is one of two things — you want language for something about yourself that is hard to explain to other people, or you want to know what to do differently. The code is decent at the first and close to useless at the second, and swapping one letter will not change that.

If it is the second, the specific facets are what you need. "INFJ versus INFP" collapses several separate things — how much you take on other people's states, how strong your internal standard is, how much you ruminate afterwards, whether you repair a rupture or wait it out. Those move independently, and they are the things you would actually work on. Two people who both settle on INFP can differ more on those four than an INFJ and an INFP do on average. Once you have them as separate numbers, the letter stops being load-bearing and you stop needing to defend it.