@Debashish Not sure what you are doing now but you have good concepts to be in top 100 and get to IITB/IISc. No need to think about anything else.
@Shiva You also have good concepts- but need to concentrate a bit more specific to GATE. GATE exam is slightly different from other national level exams like ISRO, NET, BARC etc. and it contains more numerical/theory questions similar to TIFR.