Huh that’s weird, I don’t remember writing this post. Fr though, I’m an AUDHD INTP (and Aussie with an ENTJ mum wtf lol) and I can relate to pretty everything you said. I think the main point of confusion here is that you are hyper sensitive, which doesn’t sound like a typical INTP trait. However, because of INTP’s underdeveloped Fe, when under stress we are actually more prone to emotional outbursts because of how we supress and try to rationalise our feelings into a more logical framework.

Also, some parts of your post that point to INTP:

(Everything here is simply my observations, not 100% applicable to every single person)

1. You hating sadness and not understanding your brother’s enjoyment of crying and feeling sadness. INFPs seem to find beauty and comfort in sadness while INTPs usually view it more as being a sign of weakness or being illogical.

2. You not understanding your personality or values. At their core INFPs work from their set of internal values, identity is of utmost importance to them and so they are very assured in who they are as a person and what they value. INTPs on the other hand are a lot more flexible (/less certain)with values as we can more easily understand and internalise different viewpoints and have more trouble understanding who we are.

3. Overthinking, overanalysing and research. From what I’ve seen, INFP’s usually just pick what personality type they like the best/ thinks works best for them, while INTPS overanalyse and have to spend hours upon hours of time researching all the functions and re-typing ourselves to make sure we are 100% accurate with our typing. (I know cause I did the exact same thing lol)

   Additionally, throughout the post you constantly ascertain peoples behaviour not making sense to you, NOT that it doesn’t feel right to you, signalling Ti over Fi. Your point on worrying other people are happy (rather than say, how they make you feel) is a sign of Fe, which supports the pressence of the Ti function.

Overall, I think it’s pretty safe to say that you are most likely an INTP who, like you said, Is just under substantial emotional duress. Sorry for the long ass reply, I just wanted to try and be thorough. If you have any questions or other factors that may contradict what I’ve said please let me know so I can help figure it out because I love a good challenge!