I really want to be an Englsih/ Japanese interpreter.?

I think you are fine with that major, so long as you can get your Japanese up to a high level of fluency through the minor. The most important thing is to be able to explain everything clearly in your own words, because you may not always know specific technical words off the top of your head (there are just too many). Have you heard of the Japanese Language Proficiency Test (JLPT)? A level of JLPT 2 or higher is good for interpreting.

I wish I had interpreting classes, as the answer above me mentions. Definitely look into that.

Sounds great but you really should to take some INTERPRETING classes as well. I am an interpreter and took both; I HAD to since my field/language requires me to. Your linguistics major will allow you in to all kinds of fields. Japanese will probably get you into interpreting and/or teaching the language. Good luck with everything!