FRER vs Dollar Tree Test

I am 4 days late now with on and off cramping! Checking for AF every hour on the hour. I have been testing with DT Test for the past 2 days but not with FMU. All test have been negative. Should I just opt out and buy a more expensive test or keep waiting for AF to show up! This whole TTC thing is so nerve wrecking...every month I feel like I'm being let down!