Have you identified the reasons WHY you are doing poorly in Calc BC? Are you not understanding the concepts, not able to apply them, not able to work fast enough? Would a tutor help? If a tutor is unavailable or unaffordable, try Khan Academy or go on youtube and type in the name of the concept(s) that are causing you difficulty. Many math teachers have youtube channels and it may be that a slightly different approach from a different teacher can help. Good luck!