Am I even pregnant

I missed my period last month and having symptoms like crazy, my belly even looks like I am, I'm 7w 4d. But why does my tests still come out negative? I took a first response and it was one line and one fainted but this morning I took a Walgreens one and it came out negative. Any advice ? I'm a first time mom btw. It'll really help if anyone had any advice, thank you!!!!