What a frustrating semester . . .
I am currently in an informal post-bacc program of my own making. I am taking physics with calculus (along with a few other classes) and despite my best efforts, I am getting a B in physics. I failed our last test – I didn’t understand the concepts and no amount of office hours and practice helped me understand them; by failing the test, I can hope for no better than a B in the class – even if I ace the final. 
Should I drop and get a W this semester? – only 2 weeks left. I already have two W’s on my transcript for when I first went to college 25 years ago.
If I do get a B this would be my third B in post-Bacc; I got 2 B’s last semester – but those were unavoidable: I had A’s going into those two finals, but for some reason did worse on those finals that I had expected, so my A’s became B’s. Very depressing. (My school does not give pluses or minuses, only solid letter grades).
Unfortunately, these post-bacc B’s are not my first B’s; I received many in undergrad, and even though I graduated with a 3.4 GPA, I still have 28 B’s on my transcripts from my undergraduate institutions. I went to a junior college and then transferred. Those B’s were balanced by 30 or so A’s, but tempered by some C’s, a D, and even an F. All of the C;s, D, and the F were for courses taken 25 years ago. The 28 B’s and 30 A’s were mostly from courses taken 5-10 years ago.
As you can see I have a lot of units; thus it takes many, many A’s to raise my GPA even 1/100th of a point. I would like to raise my science GPA to 3.5 and my overall GPA to 3.7; to do so will take 5 years of A’s just to do that, and B’s only hinder my efforts.
Nahani,
You might try altering the way you prepare for your final exams since you are not doing as well on them as you feel you should based on the bulk of the semester’s work. Maybe work more practice exams, hit the flash cards more often, get together a crack study group.
I definitely would not withdraw just to avoid a “B”. A “C”, maybe. You’ve got a good GPA and a few B’s aren’t going to affect it; it’ll get you into medical school if you do well on the MCAT. Withdrawals are ugly and you do not want to have to explain too many of them at your medical school interview.
Good luck!