This sounds like a really stressful situation with your sister and I'm very sorry to hear that it's manifesting itself over to your dreams

I understand what you mean by "I know I am dreaming and still can't wake up". I have this too sometime if something is really bothering me and it can feel quite unsettling.

I think that there is a lot that you are going through emotionally with your sister, that you have possibly not processed, it's almost as if you can't escape her. I think that the part that you can't escape is - what is it that your sister does, that jeopardises your wellbeing or happiness, in some shape or form? Sometimes we don't even know, hence why they come out in dreams. It could even be something as simple as needing a bit of space or your own time from her.

I hope you are able to find some peaceful rest soon