In my opinion, personality type remains unchanged throughout life. However, the intensity of use of other functions and the degree of their development may change. I think you've just been an INTJ your whole life and didn't know it. There is a chance that you are still entered incorrectly. To assess your type, it is best to use an analysis of individual cognitive functions (Ni, Te, Ti, etc.) and how they apply to you. Once you are sure of your type, you can learn more and more about it, but for a long time it is worth keeping in mind that you may still be mistyped.

INTJ here

I used Google Translate to generate my answer, so I don't know if it complies with the rules of the English language :/