Can't find the connection between low self esteem and skin picking.

I am an 18 year old female. For as long as I can remember, I have hated everything about myself, from my face to my body to my personality. I have also been a skin picker all my life. By the time I was in 5th grade, I would leave school with my hair full of blood because I would pick at my scalp all day. I've been sent home from school for having huge wounds on my legs, which they assumed were from domestic abuse, but it was actually just me picking at my legs. On rare occasions, I would make my own cuts just to have something to pick at. Once I touch a scab, I can NOT stop myself from picking at it. No matter how many times I tell myself "No," I cannot stop. I pick at my scalp, arms, legs, and face. I also have a disgusting habit of eating scabs. I don't know where these problems come from but I am permanently scarred all over my body from this disorder. It may also be important to note that I have been diagnosed with depression and anxiety (but I do not take meds), and I am a compulsive over-eater.