If you were adopted, how do you obtain your original birth certificate/other documents?

I was adopted at age 6, and the process was finalized at age 8. My current birth certificate is an official document [able to be used for passport information, etc]. It was made official by a judge who stamped it with a State of Michigan seal 8 years after my birth.

The current birth certificate has my name changed to that of my current parents, and has them listed as birth parents, along with their SS#‘s etc.

I want my original information. I have seriously considered divorcing my current family. I want to find my original Puerto Rican heritage and to get my Hispanic name back – and dump this European name.

Now that you know the background, what are the departments or official bodies I should contact?