How can I get myself help?

My whole life, I've been very disorganized, daydreamy, and inattentive. I always just thought that I was just a spacey kid. When I was 12 I suffered through depression and extreme self esteem issues. I never told anyone about it and I used to frequently have suicidal thoughts. Recently, I have been obsessed with my diet and exercise. Now I am 16 and have been doing poorly in school, I always avoid doing homework and studying and it's difficult for me to focus in class. Recently, I read an article on girls with ADHD and it seemed to match my symptoms exactly. Depression, eating disorders, inability to focus, daydreamyness, avoiding things that require mental focus. I am certain that I have this disorder, but I know if I tell my parents about it they will refuse to believe it and tell me I'm just lazy and negative. I honestly am positive that they won't take me to see a doctor, so how can I get myself diagnosed?