Don't set yourself up for failure before you even try. You haven't started your sciences yet so don't do that to yourself!! Study, get extra help and remember schools look at your overall application, not just science gpa. You still have to take your DAT, get some experience, and if your overall GPA is higher that will show you're not just a typical science major. Don't worry yourself yet. Get through the sciences and just keep pluggin' away at it. My suggestion is to start basic. Take Gen chem1, gen bio1 and their perspective labs along with your other classes. Remember orgo requires two things: time and committment. If you stay on top of it (study everyday and do all the assignments) you'll do fine. The reason why a lot of people don't do well is because they don't spend enough time on it, nor do they do the assignments. If you just attend lecture and expect it all to come together, it's not gonna happen. Be pro-active with orgo (physics too!)
Best of luck, and remember its not all about grades. They're important but not the only thing!😀