Since everyone knows it very well that hardwork always pays off. So, you can achieve your admission at such a great institution like IIT-B for sure but all you need is great dedication and smart work to acheive that because the dream you dreamt off is a bit challenging one. 

Start clarifying your concepts in Physics, Chemistry and Mathematics. Solve a paper of previous year JEE Mains and other test series from different coaching institutions to identify your weaknesses and work on them with 100% honesty to yourself.

Regards,

Keshav Sahani