discharge, lower back pain, cramping, very emotional, breast hurtd and feels heavy, gas,

I am 16 and I've been on the depo since june of 2010. I get the shot every 3 months. After myy 3rd month I never had a period since. I had unprotected sex on dec 16th 2012 and the guy I had sex with was really drunk, as was I. And he said he didn't cum, or precum. And he said he had "whiskey penis" But I was extra wet. So I didn't think anything of it. But now I have discharge, lower back pain, cramping, very emotional, breast hurtd and feels heavy, gas, extremly tired, and I took a home pregnancy test. It was positive. How far along am I? I had sex Decbember 16th. Took the pregnancy test Jan 9th. Help? Any advice would be amazing help. I'm so lost.