Well, odds are you are looking at reduction to E-1, and an Other then Honorable discharge.
For goodness sakes, you are an E-2, and you already went UA for almost a month. That may or may not be recoverable, but the drug offense is not.
So expect a month or so of restriction, extra duty, then the Seabag Drag to the main gate where you sign your baring order and get your OTH.
Just be glad it is Office Hours (Article 15), or you might be looking at a Court Martial and a Big Chicken Dinner (Bad Conduct Discharge). And trust me, I have seen scores kicked out of the Corps for the exact same reason you are.
10 years USMC
6 years US Army