RESPECTED PERSON

i m in class 12 th and now only 6 months are left for iit and board examination i m preparing for iit since class 11 thru coaching but i m not satisfied with my coaching.in phy although they hav completed the syllabus once not properly.  in maths syllabus is about to over and chemistry only 6 topics hav been done. i really desire for iit cause i know i hav potential and i understand the things well.but lack of proper guidance is big problem to me suggest me some books and the way to proceed for next 6 months.please do reply soon it is very necessary for me as well as for my family.