Ok guys, I need your expert opinions! With a 21 day cycle, would a FRER work or does it work on the basis of someone having a 28 day cycle for the HCG levels? Basically I've reached 21 days today with no show, no cramps, nothing. I have sometimes had a 24 day cycle so I thought a FRER would be more suitable than a HPT. But would it work on me? Would I have enough HCG in me? I'm so confused!