Do you think my pediatric doctor will perscribe me anti-depprestents if I'm 18?

I've been going to a therapist since I was 13, and have been diagnosed as clinacally depressed and it's getting much worse. Nothing has helped, and this is my 2nd therapist as the first one I had couldn't help me either. I'm 18, but still go to a pedatric doctor under my parents insurance. I have to go next wednesday to get a physical, and was going to ask my doctor about anti-depressants. I am going to tell him about my therapist diagnosing me with clinical depression, and tell him my situation and ask to be put on anti depressants because nothing else has helped my situation, and I've been in this state of depression for over five years and its ruining my life, schooling, and job. Can the pediatric doctor perscribe these medications? What should I be sure to tell him? I have to go to the peditrician untill I'm 19 because I can't afford or go to a family practicioner or a psychiatrist. The only reason I can afford the pediatric doctor is its under my parents insurance and the co-pay is only $15.00. I have no insurance of my own right now.