Confused ..

So, I took plan b last month everything normal happened got my period a week later.. 28-1st and then I had unprotected sex around the 15th, and a few days later I was spotting for a day or two , neither days were enough to need a tampon or anything and since then I haven’t gotten my period- I know plan b throws off your hormones and such but I’ve never had a light /spotting period like that after plan b before just goes back to normal. So I took a test this morning and it was negative I’m not sure where to go From..