Well it's already October 18, 2017 as I am writing this answer. You my friend have now TOTALLY missed the chance to have a choice of career which doesn't match your selected stream. I agree with the previous answer that you should have opted for Commerce.

Now let's focus on the current scenario. You have only a final option left:
Focus on your Boards and make sure you achieve a solid score in class 12th. This will help you gain a step ahead of most applicants and also will be helpful for the next step.

Take drop for a year and join a coaching institute in your respective city. Make sure in mind that while choosing the coaching, take opinions and make thorough research before joining, since this is your last chance to prove yourself in this SOCIETY.

Hope you find it helpful! Don't worry. Hardwork pays off.

Bhai rehen de science nhi leni thi fir
Commerce leleta ..