Your hymen is not necessarily a good indicator of virginity. In this day and age, so many girls have their hymens rip due to exercise or rough housing years before they ever even know what sex is or have sex.
Annie gives good advice regarding your other questions, and I would definitely follow it. I just wanted to point this out.
Also, please note that you were plastered, so sex is not necessarily consensual if it did happen, and there may be emotional ramifications even with the notion it might have happened being in your mind. Please don't hesitate to talk with someone, whether a close friend or relative, your doctor, or a therapist.
If you think there is a serious chance you had sex, and if it is anywhere near the middle of your cycle, take Plan B and few would point your fingers at you. If you decide to do it, do so today (tomorrow at the latest). It's said to be most effective within the first 48 hours, and not recommended after more than 72 hours have elapsed.
You should also go to the doc and discuss what happened in order to get tested for STDs.
And, I suppose it goes without saying, getting plastered and blacking out is not the best way of managing your life. I had a dear girlfriend who went in for weekend binge drinking, and it got her into all kinds of serious incidents, from unwanted sex to passing out at a black-tie formal in law school for the members of the Law Review (where she was one of the honorees). She never drank during the week, so wouldn't have thought of herself as an alcoholic, but ... read the descriptions of alcoholism and they all mention binge drinking as an early step.