You for sure seem to be coping with your Dads death with alcohol...possibly it is the escape that works for now....Just really monitor it....I feel like you don't have a "drinking" problem...but a COPING problem....I feel that way because you said you quit before and for no reason..To me that means this is a really bad time for you and that you learned along the way that alcohol takes away severe "mind and heart pain".

No one knows how you feel except your sister and apparantley she is coping in other ways...If you were my sister I would just tell you to be careful...and don't ever drink and drive...make sure you get home safely even if you have to call the police to bring you home....do not make your life worse by getting a ticket or by killing someone else...

I hear you say you are drinking the vodkas really fast...Vodka is super strong...so really make sure you take care of yourself nutritionally and hydrate a lot....Of course try not to drink as much vodka or anything else...try to make a "limit" to the amount so that you are aware that this could damage you and your Dad wouldn't want that.

I hope eventually (soon) you can get some other relief from the pain of losing your Dad...work out harder, or invest yourself more in the relationships in your family...or something else that makes you feel good and start to turn away from the alcohol....3 months ago....you weren't doing this...so it is all about your grief....

I'm sorry you lost your Father...I hope you can find a way soon to cut down or cut out the alcohol...but I wouldn't worry about "labeling" yourself with any condition during this time....