Missed Period but Negative Pregnancy Test

Hi, ladies, I need your help! I’m late on my period by 6 days. I was mildly cramping a little bit last week, but no period. I’ve been excessively tired and hungry. I’ve taken four pregnancy tests by two different brands and they’ve all been negative. When I had my first son, I didn’t experience any nausea or test positive on a home pregnancy test until I was 11 days late. Has anyone else experienced this? My husband and I are trying to conceive and I’m so hoping that I’m pregnant! Any suggestions or stories would be grateful appreciated, thank you!