could I be pregnant?

So recently last week on Thursday I went to a Womens Resource Center and took a pregnancy test cause my period was 17 days late, the test came back negative she told me to come back Thursday coming. Lately I've been feeling off, in pain like my back hurts I have headaches, I've been cramping, my boobs been in pain they've grown a little. I sleep longer , I get aggravated easy, I feel like I have to throw up but I can't. I don't know what's going on with my body I don't know what's going on. I don't know if it was spotting or not but when I wiped there was a lot of blood. I put a pad on it was nothing there afterward. I'm 21 Days Late on my period. I've also been having sex like this whole month after my period ended. I need answers could I be pregnant or not?