None of your symptoms are breast cancer symptoms, so you don't need to worry about that.  There many skin problems that can cause itching; some need a prescription medicine from a doctor, and some will clear up on there own.  No one can diagnose exactly which kind you have over the Internet.  It's not unusual for girls your age to have late periods.  When is your next regular check-up with your doctor?  If it will be soon, you can probably wait until then to talk to the doctor about your concerns.  If you have a fever or if it burns when you use the bathroom, you need to see the doctor sooner.  Let your parents or another adult know about what's happening to get some help in deciding if you need to see a doctor right away.  I'm pretty sure the doctor will have some ideas about how to help you be more comfortable.