What if you are bad at STEM?
A part of me has a passion for studying either history, political science or psychology. Lately, I have considered a double degree in pol sci + psych, what do you think?
I am not certain exactly how you derived the question but I will do my best to answer it. I personally would not recommend history, poli sci, or psych to you. Each one is flooded. Each may very well be very interesting but everyone and their mother's are doing these majors. Some because they are interested, some because they did not want to take the stem route, other just out of random selection. History is only as good as any other liberal art, Poli sci is a little bit better and maybe you will get an entry level job somewhere but it will still be very difficult, and psych is useless without a grad degree.
I want the two of us to be very clear on this. You are selling yourself short in saying you are bad at stem. Maybe you did not take to mathematical subjects and assumed you were bad as a child and that just snowballed. Maybe a teacher came along and kicked you in the teeth. I cannot be certain why exactly you have this belief but it does not have to be this way. You can learn maths and sciences with a decent amount. These are where a lot of the good careers are right now and these are careers that INTPs are better suited towards in general. I can accept you saying you don't want to major in stem but I won't accept that you can't or are bad at stem.
An anecdote, I have a friend currently at my college. Senior year of high school he could not even code for a basic website. Less than 2 years later he is one of the best if not the best person in the computer science program at my college. This could be you if you can really set your mind to it. If there is some goal you should be working on take a step to complete it now.
I am done preaching.
So much though depends on what you want out of your life and it is very likely you do not yet know. If there is anything else i can answer feel free to ask.