I'm not disagreeing wholly with these assessments but I want to present a viewpoint that I expressed in a recent thread:
"My UG curved the median to 2.6-2.8 in many premed prereqs and required doing 2 standard deviations above the mean to guarantee a 4.0 or be in the 95th-100th percentiles in the event that 2 standard deviations was unobtainable. Throw in a bunch of top-performing students into an exam and somebody still have to get the best and worst score. Plus 50% of those people are guaranteed to get scores which med schools would deem lethal."
@LizzyM (please don't hate me if you feel this was taken out of context, I can edit to include the whole post) even commented about the policies :
"What can I say, it sucks to be a student or alumnus of your UG if your plans include medical school."
These curves were not just for "weeder" courses like gen chem; they continued well into upper-level coursework, provided that the class had >30 people.
I'm not saying that my (public not private) UG institution experience is normal or that the assessments in this thread are not valid for most cases. What I am saying is that we need to be responsible with how we judge future (or current) applicants. Getting a 3.4 in a bio class at my school mean that you were the top ~20% of the most intelligent (and most gunnerish) people in the state. Getting a 3.0 in a 300 or 400 level course meant that you were pretty solid in the course since you did better than over half of the cream of the crop that made it that far.
I would ask that we keep judgements about people's personal habits or mental health solely based on GPA and no other information to a minimum when evaluating someone's chances.
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This is the end of the devil's advocate portion of this post**
OP, I am like you and had a trash (<3.2) GPA at the end of UG. I managed to get 515+ on the test and I was extremely proud of it, but that score was only because the quality of education that I received and the work that I did to learn the material was better than what other UG institutions offered or required. However, like many posters above me have already said, 528 is darn near impossible. Statistically, it pretty much is impossible.. You have to be the best of the best of the best of the best to get a score like that. Keep in mind, it's a distribution-based scoring system; you LITERALLY have to do better than the best people taking the test to be in the 100th percentile. Again as people have said before it's not even solely a test of knowledge, it's a test of reasoning capability and to some degree luck.
Keep your expectations realistic and do the best that you are able. If you don't succeed at getting a MD or DO acceptance, there are plenty of fields out there that let you care for patients in other ways than a doctor would.