Will bad grades in my first semester of tenth grade hurt my chances for a good college?

Hi! It's currently November of my first semester of sophomore year, and I'm worried my grades are slipping and this will hurt my chances for college. First of all, my dream colleges are MIT, Caltech (I know this one's VERY selective), Georgetown, Stanford, UC Berkeley, the Ivies, and others. I want to major in CS and Astrophysics. My freshman year was decent in terms of grades; I got all A's except for a B in Honors Eng. at the end of the second semester. But this year, I'm doing worse. I still have mostly A's, but I have a C+ in Algebra II/Trig. and a B+ in AP History! My math grade started out as an F but I brought it up. However, I'm really bad at tests and quizzes in general and this math class is very challenging, so I think I'm going to end this semester with a C+ or worse! :( I also feel like my grade in AP history will get worse, not better, regardless of how hard I work. In the past, I've usually ended with a 3.9 GPA, but I'm almost certain I'm going to end this one with a 3.8. I'm determined to turn this around next semester, hopefully. This worries me a lot because I've seen that those admitted to these colleges (Caltech, especially) had picture-perfect GPA's in high school. In addition to that, since I mentioned that I'm not good at taking tests, I also feel that I'll get a low SAT/ACT score. To what extent will this hurt my chances of getting into a great college, assuming I have an otherwise compelling application (extracurriculars, essay, etc.)?