Bleeding between periods

So I had my period 2 weeks ago. Just the other day I started spotting. The day after that, I was bleeding the entire day. My boyfriend and I have sex regularly. During sex, I noticed I had started bleeding. I'm not supposed to get my period for another 2 weeks. What could be the cause of this?? I went off my Nuva Ring months ago, and am not using any type of contraceptives now. Not even condoms. Could I be pregnant?? I've been partying the last week and went out clubbing last night. If I'm pregnant, this is horrible for the baby - IF I'm pregnant. SOS.