You are an ISTP TiSeNiFeTeSiNeFi
I believe that in your youth, you looped a lot as well. (Ni-Ti) So it's extremely possible that you could test as INTP. The test would pick up Introvert Thinker Intuitive Perceiver, because most of the MBTI tests are actually flawed and open for error. This is why the official ones you have an interview with a certified individual.
I have no doubt you have noticed things about your Se. You are very good at things naturally which other people aren't even if you haven't honed those skills. For example you could catch something that is about to fall, that you noticed in the corner of your eye, in a snap response to it. If someone was coming behind you to punch you, and your peripheral vision caught a glimpse of it, you might actually quickly turn around and punch them first. You have this synthesis between your Se/Ni. Bruce Lee had this and Michael Jordan has this.
Also your interest and love of the physical world/universe is accounted for in this Ti/Se/Ni combo. Sometimes your inability to remember specifics and data, can get you labeled as slow or unintelligent. It is actually all in your head very well, but other people distract you and your thoughts, just the site of their face or you picking up on their emotions can interfere with you exploring and explaining your thoughts.
You are a dominant inner thinker, who shifts perspectives well from your external stimuli and your internal honed gravity like interpretations that look at the possibilities, but with the purpose of narrowing them down to the core.
I have somehow turned this into a ramble. I also believe your enneagram type is 5w6, but it's possible that it could be 6w5.
I am an INFJ. Of all the 16 types, I am the only other introvert that shares the same internal world as you. Ti-Ni / Ni-Ti. One of my best friends is an ISTP and he is extremely similar to you and how your mind works in the description of " Crystal Computation " Steve Jobs is an ISTP and he unlocked the powers of his intuition and confidence.
My friend helped me unlock the proper focus and use of my Se in combination with Ti (I already used a lot of Ti, but it's a different beast when used properly with Se as ISTP's use it) I helped him trust his intuitions and reading other people more, without having to have the facts right in front of his face. I made damn sure to give examples in situations and prove my intuition was right too. He was stubborn at first, and I didn't like having Se forced on me. Your 3rd and 4th function will grow immensely, if you find a good INFJ friend and the right situations to grow and learn from.
Any ISTP that appears stupid to someone else, it's because they feel no one understands their internal world and as time has evolved in life, they have given up trying to convey it.
There is much more I know and could say about ISTP's that are amazing things, it's all true too. If I was living in the wild west, in the 1800's, I would want to be an ISTP. I would welcome the reduction in Fe, so I could give less of a fuck, and the increase in Se, so that I'm more attuned to my surroundings, with just enough Ni to see what's coming so I don't become " that guy ".
Surgery, Fighter Jets, Martial Arts, Physics, Teaching people through actions and the butterfly effect rather than words. ISTP's are amazing!
Please take one thing from everything I said. You are an ISTP I promise. Don't get lost in the confusion of others opinions of what it means to be an ISTP you already know who you are. We are all sensors, we are all intuitive, we all think, and we all feel. It sounds dumb to say this, as though I'm insulting your intelligence, but it's merely a reminder.
p.s. Jung was an INFJ. I'm not saying this because some other person or information told me so, I consumed all of his videos/many books, etc. to make my own determination. There is a lot of good information in "psychological types "(book), and it's understandable why Jung might think he was a Ti dom. Also your Ni is much stronger than you probably know. If you connect with INTJ's and INFJ's you will gain clarity overtime and realize that your intuition is strong and it will get stronger. Ni/Fe is nothing until Ti comes in and breaks it down.
I have a side note question. Do you ever induce emotions (fi) on purpose? I think if you go through long periods of time where you haven't deeply felt anything, you should induce it. Even if it's by your self watch an emotional movie, listen to some music or something that might bring you to tears. Even if you don't like it just let it come through you and experience it, if you fall asleep with those emotions and tears, your dreams will sort through them, and you will wake up feeling better if you just let it flow through you. I'm only saying this if you allow your self to go to long without feeling anything deeply.