HELP!! Plan B Concerns

Okay so I had sex on november 15th, the last day of my period. I took a plan B not even a day afterwards. my period is due in a few days and is it really true that plan B messed up your cycle bad? and do the symptoms of plan b show up at your next menstrual cycle? i also have a bad UTI which i am blaming my nausea and pelvic pain on. but these are also symptoms of pregnancy. but these are ALSO symptoms of PMS. help!!! so confused!! am i pregnant or not!!