Is my SO an alcoholic ?

I'm getting really tired of his drinking, I'm 19 and he's 21 and I know we're still young I haven't been drunk for over a year and a half and I don't know if that's one of the reasons I get so frustrated when he drinks all the time.

One of the reasons I stopped drinking was because when we were both drunk we would argue over stupid things and he gets blackout drunk and wouldn't remember it the next day and I'd always have to stop myself having a good time to look after him, I think it is what has really put me off drinking.

It's not just a couple of nights a week it's maybe one or two nights a week where he doesn't drink and he really doesn't think he drinks much and when I try talk to him about it he changes the subject and says he doesn't think he's doing anything wrong. He gets in such bad states and really upsets me and not only does he not remember it the next day he doesn't apologize at all and I just don't know how much longer I can put up with all this?

Also it means that I have to stay in and look after our dog when he's out with his friends cause the dog can't be left in himself and it's really making me pretty depressed, when he's sober he's genuinely one of the nicest guys ever he is so amazing but when drunk he is the complete opposite. Should I keep trying to talk to him about it ? Or will he always be this way ?

I really just had to rant and get all this out as I don't really have any friends to talk to about it so thanks to anyone who read it all :)