13 dpiui!!!! Faint postive on 88cent cheapies

Iam 13 dpiui I have been testing and got a little faint on Walmart 88 cent cheapies but when I test with frer I get negative I don't know what to think about it does anybody know if this means Iam pregnant? Today is 15 dpt trigger I don't know if it is the trigger  does anybody know this?This is so confusing.