Could I be pregnant?

So my ex and I had sex a few months ago, at the time we were together. But my last period was around thanksgiving and lasted twice as long as normal, I talked to him about it and talked to him about the possibility of being pregnant. Lately I’ve been stressing more and more about not having my period, I’ve been eating a lot more than normal, most days I’ve felt dizzy when I try to stand up in the mornings or even in the afternoon after being on my feet a lot that day, I’ve felt more tired than normal like I’ll get enough sleep during the night and I’ll wake up at 8:30 and make breakfast then go back to bed till like 1:30-2:00 in the afternoon then go to bed early like around 9:30. This is definitely not normal for me and I’m scared to talk to my parents about it. What do y’all think? Could I be pregnant? I took a test two days ago and it came out negative but you know those could always be wrong.. please help!