Yep, I think I already expressed enough on this site, about various mental health issues, my alcohol induced liver transplant and so on. To sum it up, you are like a turtle living without shell, you are never in peace, everything bothers you and in any sign of even smallest conflict, you dodge it with excuse or lie. Sometimes the consciousness is unbearable what you are doing and you simple gets a meltdown. You feel immense guilt, because your self reflection is running constantly and you know you did wrong...
It took me more than 30 years to understand what my problem is and I am on theraphy, which helped me a lot. But the underlying issue is still there and there is no good medicine for it, without some massive side effect. So I am on Pregabalin and Nicotine pouches, strange combo, but Nicotine dulls everything, everything feels less serious, things and situation don't hurt as much, you are not getting swings and so on. Nicotine in my case (something like a Zin, but from different brand) stabilize me, because without it and I emotional trainwreck. Pregabalin is massive pain reliever, mood enhancer and head closer. Open head is terrible. I don't know how to explain, but normally my head is too open, I see feel everything and that cause those things you said your sister has....and I need to have a job and normal life, so this combo sort of enables me to have normal life.
I can't speak for being bi-polar on the top of that, because if someone would told me that, I would be like ...well good luck with that... in different terms, it must be horrible.
I am only writting this for the perceive greater good, not even my family, GF knows what exactly I am dealing with. And I feel like I intend to keep it that way, given the information on the internet available, I am scared that they would feel like they are in very bad company.