HELP I DON'T KNOW IF IM OVER THINKING

Hey guys, I need help knowing if I'm pregnant or not. So December 23rd I had unprotected sex and the guy came inside me but the next day I got the morning after pill. January 1st I got my period early but I put that down to taking the pill. I stopped on the 3rd but came back on the 11th right the way through to the 15th, the blood was abnormal both times. A week after that I started getting pregnancy symptoms such as headaches, back pain, nausea, sore boobs... I took a pregnancy test but it was a cheapo one from boots, it came back negative but this month I haven't come on my period. I started back on the pill around the 8th but my normal period was due before then. But I'm still getting the symptoms. Can anyone help me as to if I'm pregnant or not