How can i clear my teen acne?

I have been suffering for really bad acne for 3 years starting as mild and working its way up. I am currently using benzoyl peroxide on and off and i have extremely dry, red skin and very itchy since using the BP. Although the last few days i have drank a lot of milk with cereal which may cause my skin to break out, but i dont think im allergic to milk, i always drank it before i got acne and my skin was fine? I have an appointment at the dermatologist in around a month, will they clear my acne? what will they use? are they allowed to give me a laser acne trreatment or am i too young (im 16). also i have used various antibiotics, BP, roll-on face stuff, recently taken zinc and vitamin C supplements?