Implantation Bleeding?

lake

So I had sex on my ovulation day (accidentally). Sunday I thought my period was on two days early. But I only spotted a little. Yesterday, just cramping. Today is my period day. I spotted a little. Having cramping, mild back pain, and nausea. It’s 14 days past ovulation. I took a pregnancy test yesterday. It was negative, so idk… I made an appointment for tomorrow. I’m super scared that if I’m not pregnant. It could be something else. It could be neither. But my cycle is pretty accurate. Everything is usually like clockwork.