Write it all down on paper rukspc. Come to her with your paper letting her know that you have difficulty in communicating and found it easier to write it and read from the paper.
Things may flow once you get started. I am sure she loves you very much and you may be very surprised.

I wish you luck with all your endeavors with your sister.

Hang in there!

Kindest Regards,
QuasiM0D0

That's a great idea to write it all down. I don't know the whole situation but it MIGHT be time for you to strike out your own. My brother lived with us for a year and it got to be too much. We got along much better when he found his own place.

I think you hit the nail on the head here.

You feel like a kid because you are still living that dynamic. She's your older sister by ten years and you're living with her family-- she's going to get bossy The bullet points you listed sounded like typical older sister behavior to me.

I lived with my mother for long enough to afford a down payment -- it was nice to buy a house at a young age, but I wish I had left sooner than I did. Independence and the ability to live an adult life is pretty priceless.

Did your sister ask you to cancel your plans to teach abroad? Would she really be upset if you did that? It does sound like a wonderful opportunity, a sort of gateway to moving out.