How long you need financial aid won’t matter: all students get re-evaluated every year, and the amount of aid offered can go up or down.
I think the Harvard NPC has an option for international students (others please correct / update as needed!). Harvard (& Princeton) are pretty much as generous as financial aid gets- if you run the Harvard one as a sample that might be a indicator of your best-case scenario in terms of what you might get in the way of financial aid.
In general, the best offers come from people who really want you, which is why your middle and safer tier options are so important: you are more likely to be a star.
Wash U in St. Louis would be a good fit for the atmosphere you’re looking for, but I don’t know if they meet need aid for international students.
My frequent recommendation for international students is Grinnell College in Iowa which has goal of 20% international students within next few years and meets full need aid for international students. It’a very good liberal arts college with very large endowment for its size. Strong in sciences and research. Location is pretty remote but you can fly in and out of Chicago which is about 4 or 5 hour drive away.
In general, good liberal arts colleges (top 30 or so) have great reputations with graduate schools because their students benefit from small classes and the focus on high caliber teaching. Because they are small they don’t have the same ‘brand’ awareness as larger universities so not as many international students apply. Still very competitive but if you are okay with a smaller school (most are in the 2000 students range) I think it’s worth seriously considering. To maximize chances you might want to focus on the ones that meet full need for international and ranked in the 10 to 25 range.
You present yourself very well on this forum and I think you will do well wherever you go. Congrats on your hard work and success in high school and good luck!