Need help

This is my February month. I took a plan b Saturday morning the 13th and I still haven’t gotten my period. Has this happened to anyone before? The 15th I bled during sex and it stopped then bled again the 16th in the morning. I’m in a long distance relationship so it’s not like we have sex all the time. 16th-20 i had spotting all week then bled the 21st like I was going to have my period then it just stopped all together. I have taken 3 pregnancy tests and all say negative. Any suggestions on what it could be? The green check marks are there when I took a pregnancy test and I used first response 6 days sooner test. Not sure what is going on with my body or if plan b has ever delayed a period. Any suggestions would be helpful. I feel like I’ve googled everything.