8 month old baby and I think I'm pregnant and im stressed out ?

So the title says it all... I have a 8 month old daughter and I think I'm pregnant again. My period is 4 days late and I took a pregnancy test at 2 days late and got a negative but could I still be pregnant? I've been having headaches and urinating more frequent, I have cramping but not period like cramps, my low back hurts too. I think I could be pregnant but I'm not sure because I don't have sore breast which is a common sign of early pregnancy and when I was pregnant with my daughter I couldn't even touch them so I kinda knew I was pregnant with her. I'm not sure what to think, it's just stressing me out. I'm not gonna lie it scares me to think that I could be having neither baby so soon. We wanted more children but we didn't think we might have one this soon but we also weren't protecting from it either so I guess we kinda knew it would happen sometime.