I moved in with my boyfriend about a week ago and ever since then I've been feeling not much like myself at all. I can hardly eat and feel nauseated very easily when I do eat. I am an alcoholic and usually drink every day.. not always to the point of being drunk but I at least get a good buzz normally. I can't drink anymore without feeling sick to my stomach which is a major problem for me because when I don't drink I am constantly having anxiety attacks. I am thinking it could be a number of things though. About 3-4 weeks ago I went back on birth control after being off it for maybe 5 months. I am no longer on the pill but now on nuvaring. My boyfriend and I had an accident and I wasn't sure if I had been on the ring long enough for it to be effective.. it may have been about a week and a half to two weeks after I started the birth control. I didn't have money at the time but 3 days later I bought the morning after pill, next choice, which on the website says it's okay to take up to 72 hours later so I am certainly hoping pregnancy is not the case.. but I am also wondering how soon could pregnancy symptoms start?

Odds are you won't be pregnant, but it is a possibility since no method of birth control is 100% effective even when used correctly.
The ring really should be in a bit longer, but at least it was there. You took the morning after pill, albeit a few days after, but that will still decrease the chance of pregnancy.
Since the feeling unlike yourself happened when you moved in, do you think it may be just some anxiety regarding that? Perhaps you just need some more time to get adjusted to it. Even if you were really looking forward to it, it is still a change, and that can cause some stress.
See what happens when you take the ring out for a period. Some women will start to feel some possible symptoms several days or so before a period is due, but it can also be symptoms of a period about to start.
The changes may also be due to the hormones from the ring as well.
On a side note... have you considered speaking to your doctor about other means of dealing with your anxiety instead of drinking? Since you say you are an alcoholic, have you looked into ways to deal with the issue? Maybe the getting sick when you drink now is a good signal that it is time to give serious thought to stopping.