First off, colleges will most likely not give much importance to IGCSE grades. I mean sure, they’ll look at them for reference, but you have to remember that you sat those exams in 9th/10th grade, so try not to rely on those grades.
Im assuming you’re sitting your IB exams in May/November 2017? First off, congrats! The IB is really hard and a 35 predicted is not bad at all. Plus, most students get more points than they are predicted (I got 3 more points than what I was predicted). I would recommend that you work your hardest on HL’s, since most colleges recommend/require 6, 6, 6 or 7, 6, 6 in HLs.
In regards to your SAT scores, those should and can be improved. these are the average SAT scores of the colleges that you’ve applied to:
- UMBC: 1290
- U of Maryland College Park: 1370
- UC San Diego: 1350
- UC Santa Barbara: 1360
- NYU: 1410
- University of Southern California: 1450
- University of Washington: 1290
- Boston University: 1370
- University of Texas at Austin: 1330
- Fordham: 1330
Clearly, most of them are in-between 1300-1450, so I would recommend that you retake the SAT as many times as possible until you achieve a better score. In regards to how to study for it, I would recommend that you use the resources on Khan Academy’s website. I found their site really helpful, and they give you access to 6 (official) free SAT practice tests. (Ps: these are just the average scores. You can certainly get in with a lower score if you extracurriculars, grades, etc. really make you stand out)
If you can, I would suggest that you try to get some more extracurriculars on your list 
hopefully you still have time (e.g: more community service, maybe start a blog to help other IB students)
Good luck! If you have any questions please feel free to message me on here Im also an international student and a US citizen.