hi disressed, i believe your family chooses not to have the capacity to validate you and your feelings. trying to explain your position won't help either cuz they r what they are. my family was/is the same way. in therapy i learned what this all was-invalidation.
can you move out of the house and have your own place? it is prob unbearable living at home. but if you have to stay there here's what i'd do:
avoid being at home as much as you can.
absolutely try not to let your sister/uncle/mom push your buttons. a way to do this effectively is to respond to anything they say with this-"i'm sorry you feel that way." if they do try "button pushing" again, and they will, repeat "i'm sorry you feel that way", etc. this way you are taking away their power. u're not engaging with responses other than the repetitive one i'm suggesting. you're not trying for family to understand you cuz they won't, distressed.
their behavior is disfunctional. you will not "win" by responding and getting upset because of it. that is their "pay-off".
it was explained to me like this in therapy-you are "tossing the basketball back to them" when you keep saying that same thing. it will drive them crazy cause they get so frustrated that you don't give them the power. remove yourself from their presence if you can by saying, "perhaps when your behavior is more appropriate we can discuss this."
i've used this in the past with a verbally abusive husband. it really works but the key is don't buy into their comments/behaviors. repeat, repeat, repeat...good luck. you can do this.