I had my period on Feb 11-14 but I had sex with protection on the 15. Just to be safe I took plan b. on the 21st I had some light to moderate bleeding for 4 days which is the normal length of my period. My normal scheduled period counting from Feb 11 is supposed to come on March 11, but I havent had many symptoms other than sore and tender breasts. I am not sure if I should count the light to moderate bleeding as a period which would cause my next period start day to be March 21. I am a bit nervous and not sure what to expect.