Took Plan B twice, Period is 10 days late…. What do I do?

Patient: I am not on birth control and I had sex however I do not know if it was protected or not. I took Plan B (the Rite Aid form) about 30 hours after having sex. My last period was on the 14th of November and usually after 21 I get my period. It is now December 15th and still no period. I did see spotting a week after taking the pill. My period was due the 4th of December and it has been 10 days past that. This is my second time taking Plan B in 3 1/2 months. I did take a test and it said negative but I am still worried. Can my cycle be this off from taking it twice?

Symptoms: No symptoms

Doctor: Hello,If the pregnancy has been ruled out first then there is no cause of worry. This is a known side effect of plan b to cause delay in next 2-3 periods and it has been frequently seen among women who happen to use it quite often.This does cause an imbalance in the hormones and thus cause the delay. It is suggested that you may wait for your menses to return and practice barrier contraception till you menstruate.I hope i have answered your query,wishing you good health.regards,