So I was really skinny as a kid, then when I hit about 8th grade I was suddenly 130lbs (at 5' 5") and freaked out so much I dropped 20lbs that summer before my freshman year, because I was so used to being so much smaller. Then all through high school I always remained between 110-115lbs, until I quit cross country and kept eating as much and gained 10-15 lbs my senior year. So that summer I lost 20lbs again because I was so uncomfortable with my weight and eating. When I started college I lost all control and gained all the weight back. This past summer I didn't have time to really lose any of that weight so I went back to college at 120-130 lbs still (at 5'6" or 7") for my sophomore year. When I came home for Christmas I had maintained the same weight, but now more than ever my family is making fat jokes about me.
I've always been uncomfortable with my weight and have always struggled with eating because of that. They're making me feel like crap and my little sister (who weighs more than me BTW) constantly makes fat jokes at me. I don't want to go back to starving myself, and I was just barely starting to accept my body for what it was this past semester. My parents don't normally joke about my weight but now they do and I'm worried that I'm actually am really fat or just ugly or I don't even know. I tell my sister to stop (since she's the ring-leader) but she won't. And my parents never tell her to stop. I have always made a point to never call anyone else fat (even if they are) because I know how it makes me feel.

How can I get them to knock it off? We don't discuss feelings and junk like that in my family, so suggesting we all 'talk it out' is useless.