Sorry for the loss mate. Although you could feel like you may be exploiting your sister as an excuse it isn't. Do not be afraid to tell people why your gpa suffered due to this personal tragedy because everyone will understand. From this point onward, think of your work as a legacy or a way of giving your sister respect. Do what you must do to get the motivation and work ethic to get As. Your gpa is far from sabotaged. You can realistically get a 3.9 or even a 4.0 if you put your mind to it and if you do, what will your overall gpa then be for your freshmen + sophomore year? 3.55
That's more than enough to put you in the running for a competitive undergrad gpa. Also realize that for the Bs or Cs you got in classes, take EASIER bcpm classes that you know you can get an A in to balance it out. This will boost your BCPM gpa. Secondly, take some easy liberal arts classes that you know you will get As in (can be enjoyable classes too coincidentally).
I think you should aim for a 3.9 or 4.0 your sophomore year. Keep your goals high and reasonable at the same time. If you are taking organic chemistry physics, orgo lab, physics lab, and some other classes totalling 15 credits or so, it can be definitely done. Good luck.
Oh yeah, make sure you eat healthy (stay away from fats, fried food, sweets, etc), and exercise at least 2-3 times a week. It can be a nice 15-20 minute jog to get the blood in the brain flowing, or some weight lifting --- point being get some physical activity. The moment you get sick in college, it is almost impossible to get any real work done (unlike in high school), and the fact that your attention becomes the equivalent of a mongolian idiot.