I think you should come to the U.S. Especially since you have already been to Spain. This could be an opportunity to get to know new country and the city you will be living in.

As you wrote, "the college in U.S is one of the top in the major that i want", I'd be inclined to think the US would be a good choice. Can you tell us which city the college is in? Others may be able to allay some of your fears about living there and perhaps even a few new friendships may be forged :). Best wishes for your future!

I'm biased since I have not lived in Spain. If you are the kind of person that enjoyed going to another country to learn, then perhaps you would like to add another country to your experiences. After school it would provide an additional choice of where to live. You would also have more international experience, and your English would improve (apparently a good thing these days). Being a little old wouldn't matter much in the U.S. Regarding fears, don't believe anything about the U.S. you have learned from the media or movies. They want to provide out-of-the-ordinary information, which you would experience less than 1% of the time here. The above is just information. My advice is to follow your dreams.