Does Headache, Dizziness And Delayed Period Indicate Pregnancy?

Hello. My husband & I have been trying to get pregnant We have been trying for about 3 weeks. I was due to start my menstrual cycle about 3 days ago. I have been feeling very nauceous, and I have had headaches off and on, dizzyness, and major breast tenderness. I have taken 3 hpt and all were negative. We have a 3 year old so I know I am able to become pregnant but what do you think I should do?.