Try and stay calm and collected, if you have been doing revision throughout the year no matter how little, you are likely to understand the content, now it's just about using time effectively to put all of the information back into the forefront of your mind. Nothing is impossible in two weeks. Get focused, get revising, keep the end goal in sight, and give yourself leisure time (within reason) at the end of the day. Find something to look forward to at the end of exams. Keep practicing exam questions and make sure you are fully aware of the techniques or exam specific skills required of you. Good luck !