Why does all the drama have to happen in my family? I am 15 and it is causing me so much stress...?

I have six other sibs. My 29 yr old brother is getting married to a b****, my 28 yr old sister just recently filed for divorce because her husband was abusing her, my 24 yr old brother has a partying / getting drunk problem, my 17 yr old sister is 6 mos pregnant, I (15) am in treatment for an eating disorder, and my 13 yr old brother sneaks out all the time to his girlfriends house or to his friends, we never know. I am really worried for my 10 yr old sister because pretty much every dinner has something dramatic going on. We are not a lower class family, we live in a very nice neighborhood with a large house and no gangs in the neighborhood, but I don't understand why we can't just be normal without the drama going on. I want us to be able to have light, fun conversations like we used to because now there is just kind of a dark cloud looming over our house all the time. I was thinking about family therapy but would it really help? Thanks<3