Hey Ellie, I can definitely relate to you as I'm sure lots of people on here can. I was always on something since I was 12/13 myself and went through stages of addiction to various drugs. Alcohol has always been there though and has progressively got worse over time as I was always told it would. I am only very early back after a relapse myself but just wanted to let you know you're not on your own and you can get better. All I can suggest is seeking out support from services near to you, groups, counselling, what ever you can get, every little will help as it is not easy on your own. Also I've had to make lots changes in my life, got rid of old friends, made sober friends, stayed away from old hang outs, got voluntary work, it goes on. Step by step it is possible to turn things around, not all at once, but you can do it in small steps.
This forum is also great, read up, post and even chat if you need support. You can change things if you want to and I wish you all the best.