Should I retake SAT? Urgent help needed.

Hi Guys.
I scored 1790 on SAT (Math: 660, W: 610 CR:520). I didn’t take any prep courses or tutoring because I couldn’t afford to. I studied on my own again and scored a 28 (English: 31, Math: 30, Reading: 28, Science: 24). I ran out of time on the Science section and that ruined my score mainly.
I want all of you to kindly suggest me if I should retake SAT? I prefer the ACT over SAT; however, ACT February testing is not being administered where I live. I have only 18 days to study till the SAT that is scheduled on 23rd January. I am extremely stressed out about getting into a good college. I am aiming for colleges such as Columbia, Princeton, and Northwestern. I have the perfect GPA, straight A’s in O and A level grades, tons of extracurriculars: debates, social work, summer programs, research internships. I have won several awards at debating championships and started many community projects. My essays are on point too. I’ve always been a stellar student but the SAT/ACT are the biggest and only weakness on my application. With such a short time is it possible for me to improve? I was also considering taking SAT 2 subject tests since instead of SAT 1 since my science score is the lowest and I believe I can score well in SAT subject test.
I can’t afford any preparation courses because my mom literally earns around $400 per month. I am an international student seeking financial aid and looking at top colleges. My background story is also really unique and I’ve really struggled (not academically) throughout my life. Do you think I have a chance of getting in competitive colleges and what is the course I should opt for? Is there any SAT Prep program that makes special considerations for any students for your program who have financial constraints? What are the best resources I can use to reach a score around 2100-2200 in such a short time?
I’d be really glad if anyone could help me out and alleviate my stress. Thank you!

I’d use on-line resources like Khan Academy or the College Board site. I don’t think that a 300-400 point jump is likely to happen but you won’t know if you don’t try. Math and CR are the areas that are weighted most heavily on the SAT format that is being phased out currently.

If you have the time and the money, you should definitely retake to make yourself a stronger applicant. However, there will be a late fee if you want to take the January SAT (which is the very last old SAT), so that wouldn’t be so good for you. IMO, you should focus on the ACT. Good luck with what you do!