You are smart, hard-working and tenacious. All good things.
You need to flip the model you are using to evaluate colleges. If you are getting no need based aid, and your parents won’t help you financially (or fill out FAFSA), then the ONLY criterion you need to focus on right now is getting a bachelor’s degree in four years, without debt, at a recognizable university with good advising, professors who can pick up the phone and call a former student or a colleague and say “You need to hire this person” (or-- “I’m writing a recommendation for a fellowship and she’s fantastic”.)
You do not have the luxury of worrying about what happens ten years from now or law school or getting a Truman/Marshall. You just don’t.
What you DO have-- like I said, smart, hard-working and tenacious.
Things like Truman/Marshall, Peace Corps- these are competitive. You can do everything right for four years and still come up dry. But that doesn’t mean your life is over- it just means you need a solid plan B.
Put the specialized major aside for now-- I know people at the UN, World Bank, IMF, and you’d be stunned by how varied their degrees are- history, languages, economics, agronomy, geology, oceanography, literature, political science. There are lots of different paths to one of the many careers you are describing, and if you cut the salami too thin right now, you’re going to miss out on many great opportunities.
And don’t over-value the presence of international students on campus. My own kids went to colleges which had very high percentages of international students. To my great surprise- there was VERY little engagement. The wealthy international students did what wealthy students in the US do when they get to college- and if you weren’t part of the “go into the nearest city and eat in expensive restaurants and clubs and concert scene” (my kids were not) then you were just not going to get their “international perspective” up close. And the not-wealthy international students hung out with other kids from their country (many of whom they already knew from elite academic competitions or summer programs), cooked for each other in the dorm kitchens, and studied together. Many of them were being funded by their home governments and knew they were going back immediately after graduating, so the incentives to make “local” friends were pretty meager.
You are more likely to have a roommate from China or Ghana or Pakistan at a college with a smaller international population- because those kids won’t know ANYONE on campus from home and will be thrilled to make a friend!