CONGRATULATIONS on an impressive record - JPLT N3 shows real strength in an area outside your top field and your results in chemistry should garner interest at all the colleges you listed.
Running the NPC is a very important first step so that international students and their parents understand costs at US colleges. If you live in a country where 8K tuition is considered exhorbitant or where the average middle class family makes $800 a month, these numbers matter a lot.
Students can just enter the info for domestic students and remove any non institutional aid from the financial aid package (ie., Pell, anything with “federal”): this is the lowest amount your family will be expected to pay. When parents are divorced, both parents’ income are factored in, even if one refuses to pay. If they remarried, their spouse’s income also factors in.
Cambridge may offer you a scholarship but other UK universities are both safeties academically and probably out if reach finanfially. Talk with your parents wrt costs there, too.
You need to expand your list though and in particular find 2-3 universities your classmates aren’t applying to.
I’m thinking of Northwestern, Rice, URochester, Vanderbilt, HarveyMudd, USC in particular.
Perhaps Williams, Swarthmore, Vassar - those would definitely be under the radar at an entrance-exam Stem school in Singapore. If your budget of 20k is a true estimate of your parents’ ability to pay (rather than willingness), Amherst and Bowdoin would not consider your need in making a decision, just like HYPM Brown Dartmouth do.