What you are doing isn’t working for Calc. Check these tips out:
http://talk.collegeconfidential.com/high-school-life/2026961-what-to-do-when-you-arent-doing-well-in-a-hs-class-p1.html
Did you take Pre-calc last year? Calc as a junior is pretty advanced.
Did you take Chem/honors chem already?