You'd need your hCG measured to find out if you're pregnant, and that wouldn't be showing up on CD21 - well, most probably not. That's why home test kits, which also measure hCG, don't work on CD21; the egg has to implant for hCG to be made.

Our lab has:
Progesterone reference ranges:
Follicular phase: 0.6-4.7nmol/L
Ovulation peak: 2.4-9.4nmol/L
Luteal phase: 5.3-86nmol/L (yes, 86, not 8.6)

HTH!