Late period

Hey girls, I took Aftera (cheaper version of plan b) right around ovulation. A week after I had brown spotting for 2 days. My period was due 2 days ago and no sign of it. I’ve been very moody and sensitive for the past few weeks & I’ve also had tender breasts and episodes of nausea, but never actually threw up (these symptoms have been present for a few weeks). I just took a pregnancy test and it came back negative. Has anyone ever experienced this? It’s been over 2 weeks since I took the emergency contraceptive. Could I be pregnant but too early to test, or maybe too late in the day and it was purely water? Any feed back helps