In the beginning of December I got my period and a week later I had unprotected sex. He didnt pull out on time so the next day I took the plan b pill. A week later, I got my period yet again even though I had already gotten it. It's now the almost the end of jan. and I still have not got my period. So I decided to take a pregnancy test but it was a really cheap, untrustworthy one and it came up negative. Did the plan b mess up my cycle or do I need to wait and take a trustworthy pregnancy test?