escesc, you need to keep in mind that the MCAT is a thinking test. yes, you need to have basic knowledge in the sciences, and yes, there are some things that you need to memorize, but overall, it is mostly a thinking test. Considering that your science GPA is reasonable, it seems like you got a good grasp on the material, so I wonder if it is your application and interpretation of the passages that did it for you.
When you go back through your practice exams to see what you got wrong, did you ask yourself why you got those questions wrong? Was it because you didn't remember something you should have from your classes, or was it because you didn't understand the passage. Especially since English is not your first language, I have a feeling that your problem might be that you have difficulty understanding the passages and are not used to the way that they present the information.
With that, my guess would be that you might not need to study the material, but rather do more problems to familiarize yourself with the style of the questions. For this, I found EK's 1001 Physics and Chemistry to be not very useful, since basically all of the questions in those are discretes, as opposed to the passage-based questions that predominate on the MCAT. EK's 1001 Biology and 101 Verbal books are good though. Also, since you did Kaplan, you probably have access to the question bank. I hear that is a tremendous resource.
Definitely doing as many practice tests as possible would help you.
So retake or don't? That question is really up to you... Do what you think feels right. Do you think you can get a better score if you retake, or are you planning to retake because you think you might get the luck of the draw?
If you do retake, don't rush into it. Take the summer to study so that you are well-prepared and can go into the test confident.
Best,
kirkio