Hi, there _future_do.
First, we need to look at your priorities. School has to be top, but you also have to take a realistic inventory on how many classes you can handle and do well. If it is only 12 hours a semester, so be it. Its better to take a little longer and do really well than to bite off more than you can chew and do poorly.
The next step is to visit a counselor or help center at your school. Most schools have some sort of students services office that helps students to develop better study skills. You need to find out what works for you, and then use that strategy to get As. If you want to be a doctor, then mostly As is what it has to be. Mostly, school isn't quite so tough if you get your mind right about it.
I find that with a lot of students, its their own anxiety that gets in the way of succeeding. They put so much pressure on themselves that they forget that the purpose of school really is learning, so that you can apply that knowledge later. So, take a deep breath and relax. Then, decide that you are going to honestly learn the material.
The first step is to NEVER NEVER CRAM. Start studying for the next exam the day after the last one. Read all materials before class, if you can. Take notes while you read. Don't copy verbatim what you read, but summarize all concepts in your own words. Focus on each concept until you understand and can explain it to someone else. Then, move on to the next one.
The next step - NEVER pull all-nighters. Sleep is very important. Its when your brain digests what it has been through that day. Sleep improves memory, whereas exhaustion negatively impacts your recall. Get regular sleep. Set a schedule for yourself that includes classes, study time, recreational activities, and bed time. Try to create as much balance in your life as possible. If you can't do that know, then you'll never be able to in medical school. Having fun helps you to release stress. Less built-up stress means that you can focus on your studies better.
You got a 33 on the MCAT. Obviously, you're very capable. If you take the steps know to improve your study skill, you'll be fine.