Really need some help!

Ladies, I am not TTC but I am 8 days late as of now. I have been under stress lately but I've been through a lot more stress in the past and my periods neve went missing/late because of it. I have been taking tests literally all week. I've spent 49$ on tests so far. But Thursday afternoon I took a test---the first one in the picture--- it stayed negative for hours, I checked it again right before I went to bed and the next day when I looked at it there was a line there that wasn't there the previous night day. So seeing the line I went out and bought more tests. I got a first response again and I also got a clear blue digital. They both came out negative. Later that night I took a clear blue again, also negative. I still have another one to take which I'm going to wait until next week to take but ladies I am utterly confused. Please help a girl out. I'm thinking that the first test was a Evap line.