Anorexia?

I'm 18 years old and have never weighed over 117 pounds. Since I was about 15, my normal weight was about 115. I decided I wanted to lose weight almost two months ago when I was at 117. It took me almost a month to drop a pound...so I started eating less and would rarely, but occasionally, throw up. It didnt take me long to drop down to 114. A few days after, I weighed 112. I thought it may be the fact that I was on different scales. A week passed and everyone noticed I had lost weight. Not to mention I could slide off a size 1 jean without unbuttoning or unzipping them and a lot of my clothes were getting a little baggy. I also went back to a dress size of 2. I will sometimes make myself throw up something like cake or anything unhealthy I allow myself to eat....and right now i just really dont know what to do. I want to stop because Im scared. But I love feeling skinnier. Do I have the onset of anorexia?