First of all I think one or two good books are enough. Dont go nuts for number of books.
For Maths, first make sure that you remember all the formulas, Use TMH for this. To regain confidence.. try to understand few solved examples of a chapter before you start solving unsolved once. Once you see a question and you are sure that you can solve that problem very easily and you know all the steps.. then you need to write answer while practicing, you will be wasting your time.
I think at this time you should stop taking test series for now and first complete your whole coursework in depth. Then once you are satisfied with your preparation then you can go for test series. Remember .. as I have said earlier " Its the time to learn .... not to show"
Best of luck
PathFinder
Technocrat
IIT Delhi, 2004 Batch
Currently in Student Counseling & s/w Industry