Online classes have honestly become a boom . Taking up  science just because there are no good teachers around you for commerce is not a reason good enough for forgoing your interest. I would like to share my personal experience with you . I did not take any coaching in class 11 and 12 for any subject except maths and that too in maths most of the syllabus I had to cover by self study only and I scored 97.25% aggregate in my boards.

I would suggest you take up online coaching and if you are not ready to pay the fees then you can take help of free classes on youtube . There are a number of teachers teaching on youtube for free. Believe me you'll ace your exams if you have confidence in yourself.