You must be excited about getting to travel.
I think you will have more experience of different cultures than you think. The US is a massive country with very different cultures within it.
I live in Scotland - a tiny country and it has massive differences in culture in it. Glasgow and Edinburgh are a 45 minute train ride apart and could not be more different places to be. The Western Isles in Scotland have their own cultural norms as well.
There are different norms as well depending on age, social class etc etc etc.
And then within each group are people who don't fit in with the norms.
If I were you, I would get to know people as individuals. Find out about them and their attitudes toward life, love, sex and friendship and see if they match up to your own.