88 cent Walmart pregnancy tests

Kyrsten • 24, married 8/2/2014, Gracelynn Rae born 11/27/2015, baby #2 due 10/25/2017 ❤
I took one of walmarts cheapies last night and it was negative. I then read that those test are for use the day of your missed period or any day after your missed period. Are they not sensitive enough, are FRER more sensitive? My periods due Monday the 6th. I feel like the cheapie would have picked that up by now.