How? You were first generation before your grades dropped too.
The very highly competitive schools for admissions expect your grades to be maintained.
But really…as noted…one or two B/B- grades will likely not be the reason you don’t get accepted, if you don’t. And if you don’t get accepted, you will never know why. There are many students with perfect GPAs who are denied admission at these colleges. There simply aren’t enough seats to accommodate all of the very stellar applicants.
I will add…your ECs will not likely make up for your GPA…but then your GPA shouldn’t be that much lower with two B grades.