What Causes Delay In Menstruation, Swollen Tender And Heavy Breasts?

Hello. I had unprotected sex on nov. 23rd. Took plan b 2 nights later and had gotten a light period that lasted about 4 days 2 weeks later.It is Jan. 6th now and I have gotten nothing but negative tests along with breasts so swollen, tender, and heavy. Could I still be pregnant?? Or could these symptoms be prolonged side effects? Thank you! !!