BFP frer, bfn digital

Taylor • Married. Brooks born 8/2015. Baby Eleanora Quinn due May 2018. 💞
I got faint BFP on 3 FRER tests today, with FMU and also this afternoon. AF was due today. I decided to take a FRER digital, too and it showed negative... Are digitals less sensitive and it just may not be picking up my levels yet? Or is this a false positive?? Confused!!