Its time to start panicking. Do a set of exam papers ( calc and non-calc every week. Compare your answer to the marking scheme. The answer is not good enough all the working is required. Look at their working out in the marking scheme. How many marks would you get. Read the examiners report for each exam. It helps you know where others went wrong and perhaps how to avoid the pifallls.
Many schools don't use a Maths book. The revision guides are ok but a real Maths book with lots of questions are so much better. There are many to choose from amazon.
These books can help but any are good
Try to attempt one question from each section or exercise of the book each time you revise. It should take a little over two hours - almost the time of an exam paper.
Ideally you need to do this once or twice a week if you want a good grade.
The difference in a grade is about 2-3 hours of revision, so if you want the grade then you must do the learning. Maths is about practice as well as doing the learning how to do it.
Generally know how to do a sum is not the same as doing it.