OK, so like others have said, abstaining from alcohol is a plus in many ways, but I understand that it might be the only way that you're used to socializing with people, so this is a negative consequence. Regarding mirtazapine (Remeron), I have some experience with it in varying doses and I must say it has some pretty noticeable side effects. While on it, my appetite was voracious. I gained 30 pounds in 2 months; no exaggeration. Also, it's caused me to nod out so severely, that family and friends were "positive" that I was back on heroin.
I eventually found the side-effects of mirtazapine to be unmanageable so I quit taking it. In the end, antidepressants can be helpful, but if the negatives are outweighing the positives, then maybe it's time to re-evaluate your situation.
However, if you're not willing to stop taking it, then skipping a dose would probably be a good solution to your problem. Compared to other antidepressants, I always found mirtazapine's effects to be rather accute. I wouldn't recommend using amphetamines to counteract the mirtazapine. The more substances you combine, the more likely you are to experience unwanted side-effects. Especially so with alcohol.