Help girls

Has anyone else been convinced there pregnant but got negative tests and then a positive? I got a really faint line on a test two days ago but I’ve just taken a really cheap strip test and it’s negative but I don’t know if it’s just because the test it so cheap 🙁 would it be best to just go and buy a digital and ignore the cheap ones? I’m 7 days late for my period so it’s not like I’m testing early.