Cell bio and o-chem shouldn't be that stressful for you. I'm taking O-chem w/ lab, cell bio, genetics, english and a low-end physics class right now. At first I thought I had an impossibly hard schedule, then I realized I was just being lazy and not studying nearly as much as I should.
Like everyone said, be organized with your time and study smart. If you need to study three hours for every hour of lecture in even o-chem, it sounds like there is something wrong. I can usually grasp an entire lecture just by re-reading what he lectured us on a few times, which certainly doesn't take three hours.