Pregnancy test! Help a girl out!

I'm not on birth control and I think I may be pregnant. According to this app I'm 6 days late. I took a test a couple days ago and it said I wasn't pregnant. I don't see any signs of getting my period anytime soon like I usually do. No cramps or mood swings. I'm debating if I should take another test. I need advice! Is there a test that would be more accurate than others?