Glad you came to SR. There is a lot of love and wisdom here.
I didn't see in your posts (and if it is there I missed it - sorry) whether or not you have considered going to Alateen. They are meetings for teenagers who have a family member or friend who is an alcoholic. Everything is confidential and no one will laugh or make fun of you there because they have all been through it. Nobody will talk about what you say at meetings - heck, the first Al-Anon meeting I ever went to, I walked in and there was my high school Spanish teacher (whom I adored). I almost passed out! And my XAH sponsor turned out to be a guy from my hometown, which has about 750 people in it, so I was terrified someone would find out what was going on. Never heard a peep from anyone.
It sounds like you have a lot of responsibilities on your shoulders at a young age, and for that I am sorry. You have probably seen and heard things someone your age should not have, and so have your brothers and sisters. If you can get into Alateen, Alanon or counseling, not only will you make yourself healthier, but you can pass on your strength to your siblings and help them too. I am assuming "Uni" mean "university" on this side of the pond so I bet your college health department can give you some info on meetings and such.
But at least you are recognizing at a young age that you have issues and you are working to solve them. That is really going to work to your advantage. You seem very self aware and that is wonderful. Awareness isn't always pleasant, but you are far ahead of where a lot of us were at 19!
Best of luck and I will be thinking of you today.