You had unprotected sex and take postinor-2 after 14 hours, i.e. within the first 24 hours. Postinor-2 is an emergency contraceptive
which prevents pregnancy
even if taken after 72 hours.
However, the earlier you take it, the less the chances to get pregnant.
As your HCG
result was negative, and you took 2 postinor-2 pills, then, no chances for pregnancy.
All the best and enjoy life!