Here's the deal.
1. You're in the wrong forum
2. If you can't handle OChem 2 and micro, you can't come close to handling medical school. Now being on the other side of the fence, undergrad is so easy its not even funny. I take a lot of questions from undergrads wondering if they can handle psych + a real class and if 18 hours is too much. It might cut into your xbox time, but think about what you want to be when you grow up.
3. On the flip side, dont feel like you HAVE to take a hard schedule because you want to be a doctor. Enjoy undergrad. But make yourself competitive, its a fine line. If you dont think you can handle it (you probably can), you probably just dont WANT to handle it. That's fine. Nobody in undergrad has a gun to your head and is saying "pretend you're in medical school"
4. I always took hard semesters because I was double majoring and thought I had to. I got accepted in the fall and planned a CAKE (bunch of pass fail, etc) senior spring. Best time of my life. Medical school is somewhat of a culture shock, its different. Definitely get your fun (to a certain degree) out, because things will change.
Good Luck