Hi,
I was looking through posts and yours resonated with me, because I too have an ability to feel others energy. Having that sixth sense of being able to feel peoples energy can be positive or it can be draining and negative. I can see how you may want to help people, especially your sister, if you notice that something is not quite right.
I had a life coach once who was helping me on some areas of personal growth, and one of them had to do with my husband. She said, " What your husband thinks and feels is none of your business." I was taken aback by that and had to think about if for a while , and then tried to practice it. At first I had difficulty, because you would think that partners should be able to share everything, especially when you see them struggling. And then I realized that the more I tried to be involved with his thoughts and feelings, the more it irritated and drove him further away.
It took months for me to be able to detach from his thoughts and feelings and just stay present, available and keep doing "me". It took a long time to shift but once I did I felt so much better about myself and about our relationship. I also noticed that he was calmer and not as agitated around me and we slowly grew closer together. It was a find dance but it worked.

I dont know if this is helpful or not, but your internal conflict resonated with me.

Thanks for sharing.
Gabrielle