Welcome from me too. I can see what a lot of responsibility you have taken on your shoulders, while still so young. I am so glad you are getting some help at college and that you have come to this site too.
As Charles has already said, you do not have to carry all this on your own. Do try to get into some of the Support Groups and chat with others (Family and Friends Support Group will probably be most useful for you – see the list under Support Groups) and exchange thoughts and ideas with people on the Forum, as you have just begun to do.
Again, as Charles has said, it sounds like your Mum would benefit from support, including information about this addiction, too.
You show great strength of character and concern for your whole family circle. You have probably got wisdom beyond your years. So cherish yourself and allow yourself to be cared for, too.
I really wish you well as you seek day by day the right ways forward for you (and the family circle).
Monique