I am on birth control and will be for three entire months next Saturday. I missed two pills on May 14th and 15th, however i doubled up on pills on both May 16th and May 17th as the instructions say to do. I had unprotected sex May 17th but he pulled out (this was the day before my placebo pills start). Also, on May 20th, BEFORE the 72 hour mark I took plan B just to be safe. 18 days after sex, on June 3rd, I took a blood pregnancy test at the gynecologist and it came back NEGATIVE. However, today, the 7th of June, I woke up and bled a little bit and have been bleeding throughout the entire day. It is mostly noticeable when i go to use the restroom and I wipe. Could this be implantation bleeding 22 days after I had sex... or could this simple be the side effect of plan B and I am getting my period a week early?