Natural born staying abroad Would like to know about my US citizenship status.?

Hi, my parents are Malaysian citizen and I was born in the US while they were studying there in 1980-1986. We came back to Malaysia when I was 7 month old and thwy registered me as a Malaysian citizen. Now I'm already 24 and would like to know about my US citizenship status. . The only doent I have is my birth certificate. Must I declare my citizenship to the US emby here? What else should I do to claim my US citizenship if I am not one?