my language background

At home I am speaking german because my whole family is german and they are not bilingual so there is only german. However my parents are able to speak English because of their work but it is not enough to communicate in English at home. So I learned english since the 5 grade of school. In school we learn mostly british english ant the first time I came to America I was wondering how different the pronouncation and spelling in these two differnt Englishes is. Now when I am in my room with my roommate I don't think about how I say things so there are may many mistakes because it doesn't have to be correct. But when I come to class in the college I try to speak grammatically correct english and that's really hard for me because I don't want to do any mistakes. However I try to improve my english by listening carefully and asking abut my mistakes.