@cmuben if you did take the BC test in May as I suggested and you got say a 4 or 5 on the BC portion of the test, would your school allow you to go on to Linear Algebra or Multivariate Calculus? This to me seems like the simplest solution for you.
I agree. If you can swing it, there are a few topics from differential calculus that appear in BC but not AB, like L’Hopital’s Rule. The big difference is Taylor series.
There is an online course specifically designed for this. Use this from EdX
https://www.edx.org/course/ap-calculus-bc-0
Sign up for the BC Calculus exam in May, not the AB exam.