Could I be pregnant?! Help!

So I'm a bit desperate for some help here. I am very confused, My period was supposed to be here on the 25th, 12 days late. My periods are pretty regular, and my flow heavy, so when it failed to show up I took a test. It was negative, but a few days later I started spotting, and that first day I was hit with a wave of nausea and threw up twice. The day after, and the day after that, I threw up around the same times. The light spotting has continued for maybe a week now, it has changed in color from light brown/pink, to dark brown and darker red. It's very different from my period however, when is heavy, dark, and lasts about a week. I took two more tests this week and they were negative. I would just think it's my period, but for some reason it's off, but I never get sick, and my appetite has changed. I'll be starving, but can't eat more than a few bites! I'm so confused and worried. I hope I'm pregnant, but if not than I don't know what going on. Please anyone, I'm in need of some helpful advice!