Opheliamg - I'm going to give this a shot.
You sound like a fantastic applicant and I want to highlight that 8 II's is really terrific, so congratulations. To answer your questions: No, you probably do not have any red flags on your application. I think there are 2 reasons you are recieving less II's than you may have expected:
1. schools, especially the top ones, have an idea of what type of "mix" of students they want in a class. Certain amount of "this" type and certain amount of "that" type (research, community service, athletes, etc), and you might simply be a "type" that comprises a large portion of their applicant pool
2. While your stats are stellar, you haven't demonstrated some of those "it" factors that help push applications through. I want to emphasize that this is in no way a diminishment of your hard work and character, but just a reality that there are other applicants out there who have achieved what you did, or close to it, but throught very difficult circumstances and adcoms will look at those applicants first. I had a 3.9 GPA and MCAT of only 32 (equivalent of current 512/513?) and got 13 II's, now attending a top 20. It was my personal statement that got me through the door (definitely not my MCAT) and some other unique extracurriculars maybe. Again, this does not diminish your accomplishments and capablilities; the reality is that there are lots of other excellent applicants too with compelling stories/backgrounds.