Tbh, I get the feeling that you're probably posting this in the hope that people will tell you not to bother so that you feel better about doing so. It is never too late to start revising - why would it be? Any revision you can do is going to be better than the alternative - i.e. giving up, doing nothing and accepting that you are almost definitely going to get worse grades than you wanted. Use your time effectively, and do as much work as you can to make sure that you don't regret what you do in these next few months when you look back in later life. Best of luck with all the exams