A single delayed tablet should be taken as soon as possible, and if this can be done within 12 hours of the correct time, contraceptive
protection is maintained.
With longer delays, additional contraception
Only the most recently delayed tablet should be taken, earlier missed tablets being omitted, and additional non-hormonal
methods of contraception (except the rhythm or temperature methods) should be used for the next 7 days, while the next 7 tablets are being taken.
As you had unprotected sex on 16 day[risky- as ovulation occurs around 12-14 day]; perform urine pregnancy
test after 2 weeks on early morning sample to rule out pregnancy.
I hope I have clarified your doubt.