Every test says INTJ but I procrastinate constantly. Am I mistyped?

You are probably not mistyped. You have hit a place where the description bundles two things that are actually separate, and you have one of them.

Planning and follow-through come apart routinely. In trait terms they are different facets under the same broad dimension, and they correlate far less than the word "conscientious" implies. Detailed plans plus slipped deadlines is a common and coherent pattern: high on order and structure, low on initiation. What the description does is take the pole labelled J and describe someone who has both, because it has one letter to spend and cannot report a split. So when you read it, one half fits precisely and the other half indicts you — and the natural conclusion is that you must be the wrong type, when in fact the type had no way to describe you accurately in the first place.

The split is worth taking seriously on its own terms, because the two halves have different fixes. If your problem is initiation rather than organisation, better plans make it worse — planning is the thing you are good at, so it becomes the sophisticated way of not starting. What tends to move it is shrinking the first action until it is too small to need a plan, and separating the decision to start from the decision about how to do it well.

One caution on the self-diagnosis: procrastination that is really avoidance of a specific feeling looks identical from the outside to procrastination that is a follow-through problem. If the tasks you avoid are consistently the ones where you might be judged, that is a different mechanism and planning tools will not touch it.

There is a way to get evidence here rather than reasoning about it, which is worth doing because self-report on your own discipline is the least trustworthy self-report there is.

The self-report side is a follow-through scale: how you handle a broken streak, whether you restart small or wait for a clean slate, whether you plan around your worst days or your best ones. Then compare that against something recorded rather than remembered — how many guided sessions you actually finished versus abandoned, over a couple of weeks. The two numbers disagreeing is the interesting result and the specific one. Someone who rates themselves poorly on follow-through and completes most of what they start has a self-image problem, not a discipline problem, and that is a completely different thing to work on. It is also the more common of the two among people who describe themselves the way you just did.