People do more damage than good when they give smug "advice."
I know the feeling. The good thing is sometimes you gain power by not talking. It makes people come to you.
I don't want to get married or have kids and I always have people telling me "Oh, you'll change your mind one day" or "Oh, you just haven't met the right guy yet, just wait." So I know the feeling.
What I want and what my body wants are two different things. I don't let my hormones control me. (Not implying anything against your sister, I'm sure she had reasons for changing her mind).
The one who holds the most power in any relationship is the one who cares the least.
I have found an interesting way to deal with this. Try asking whomever it is who is telling you these things, to share their reasons why they believe this for you. It's a way to make them think about why they say it, and can open up discussion for mutual learning. It has helped me direct a few people in my life, to truly seeing exactly what they are doing, and how they are minding MY business, rather than their own.
I've had this done to me before. Just do the same thing back and see how much it pisses them off.
I don't like this push-and-pull concept. Ghandi said, "An eye for an eye makes the whole world blind."
This happens to me... far more than I could ever like to think about.
There is nothing more maddening, to me, than being told,
"Oh, you don't really think that."
"Oh, no, you can't really want to do that."
"Oh, you don't like that."
Etc.
Does this happen to you?
How do you deal with it, on an interpersonal level?
And, most importantly, how do you deal with it within yourself? I feel like my soul's been drained when this happens to me, and it drives me crazy. This has been happening so much to me as of late (mostly from one person... but that's besides the point) that I am just shut down. I see no point in talking when people already, "know everything that I'm thinking and feeling".