Student Exchange Programs

i’m an exchange student from Germany and i’ve been in the state for about 5 months now.
I really like it here and the closer the end comes the more it crosses my mind to stay here. My parents would also like me to continue and finish high school over here. Now I have a few questions that I was wondering about. Does somebody have experience with that? I’m intending to talk to the principal and ask about the credits you get and if the german credits count too.
If it should work out with that, what is with the Visa? Will I get another Visa/Studentvisa if I have a place at a high school? I’m turning 18 soon, so i’ll be a legal adult.

Would love to read advices and about your experiences!