Try writing it down in a letter. You don't even need to give it to the person until you feel more ready. But maybe writing these feelings down and expressing them somewhere will help you gain the courage to tell those that matter. And then it's literally just handing them a letter. You won't have to find the courage to put words together because you already did it in your letter.
At least that helps me when I'm trying to say something difficult - no matter how I think the person will react.
Small steps at a time. It sounds like your sisters will be supportive and they may already have a feeling and are just waiting for you to come to them.
Just know you aren't alone and we are here for you as well ❤ ️
You got this hun, and once it's out there - it's done and no longer something you have to do alone. It can be very daunting but also very relieving.
29 here. Just realized I was trans so worried I missed out on being able to pass as I transition 😞