If you got 5 on BC and the AB subscore, then you should be strong enough student in math and have a good knowledge of calculus, so that you should not be afraid of introductory statistics with calculus or multivariable calculus.
Your teacher actually does things more like college does in basing the grade on tests. But it looks like his/her tests and grading is relatively grade-deflated compared to AP tests and grading, unlike the usual case where high school grading is inflated compared to AP grading. However, actual college courses in multivariable calculus and introductory statistics (with or without calculus) will be semester long courses, rather than year long courses that they may be in high school.