Good day. On 7th july, i had dry humping naked, i took plan b 16hrs later. 5 days i had withdrawal bleeding for 4days, 20days later i had my period which was more than a week late. My period is 6-7days, but this time it was for 4days, the first 3days was heavy, on th 4th day it reduced, the fifth day they was no blood, just a little drop of brown discharge. Is that normal?? Can plan b reduced the duration of my period, with that can i be sure i’m not pregnant??