Are my parents alcoholics?

im going through a really tough time at the moment because im suffering with OCD. this means that im stressed alot and my parents drinking is not helpful at all.

my mum and my step dad down 2 bottles of RUM on average every day. thier moods are always up and down which is hard to deal with. ive tried confronting them about it but i always get told off, and they say that it is a normal amount to drink and they dont have a problem. i disaggree. this is really started to affect me now. i cant take it anymore; i have been so stressed i have self harmed and i also thought about running away.

my step brothers and sisters aggree with me but they do not live with me so i hav no other support, and they will not say any thing.

1. are they alcoholics??
2. what shall i do?