Had SAD a while back, now depression for a while. How would I get anti depressants?

At the age of eleven, I suffered from untreated separation anxiety disorder. I tried to tell my parents about this, but they just deemed it a "phase" because they're the sort of people who don't want to admit that their child isn't "normal". I am almost seventeen now, and for the past few months I have been through (I'm pretty certain of this) depression. It's affecting my school work and my relationship, and I believe that anti depressants would do me well. However I don't think I can approach with my parents with this problem, and I don't want to just "wait it out". Any suggestions?