I am scared of going to Japan!?

I have lived here in the US more than 9 years. Since I came here, I have been to Japan only one time, 6 years ago. I actually don't miss Japan so much. I feel comfortable with living here, even though I still have a problem with my English. I have more friends and activities here. I can also get a lot of Japanese things and cook Japanese food here, if I want to.
But my parents in Japan miss me. They are getting old, and I think I should go visit them in Japan. I also want to bring my boyfriend with me. He is interested in Japan. So I'm planning to go to Japan this year, though I still haven't decided any details yet.
I'm excited but also a little nervous because Japan is like a foreign country' to me now. I'm completely used to American culture. I forgot many things in Japan and I don't know how it has changed. I will be embarrassed to do something wrong in Japan. I might not know how to take a train or how to buy stuff, like if you go to foreign country for the first time. I can speak Japanese fluently, but I am afraid that I might ask strange questions. I look Japanese, so they will just think I'm stupid.
Oh well... it's still exciting. I will find many interesting things in Japan.