I'm on Nordette and got my normal period the right time. I stopped for about a week when my period came back for no reason. I didn' forget to drink my pills and I am taking them the same time every day. This period just won't stop and is going onm for 3 weeks now. The colour changes from red to dark and then a light red. What can be the problem?

3 weeks is too long for a period that is supposed to be your normal, annual period. You should go to your doctor about this. Either call them or make an appointment. You really should do this if something happens that is abnormal for you (I'm sure being on your period for 3 weeks falls under this category.) But you should especially since you are taking pills. GO TO YOUR DOCTOR.