Had unprotected sex on b control three days after stopping azithromicin.. is that safe, since it was after stopping antibiotics?

Small risk.: Azithromycin may reduce the effectiveness of hormonal birth control tablets although the risk is small. To be safe it is recommended that another method of birth control ( condoms) be used for the time you are taking the antibiotics and then for another 7 days.

Antibiotics and OCPs: The combination can reduce the level of hormone circulating in the body and make it easier to get pregnant. It is best to use a condom until your next cycle if you want to avoid pregnancy. Antibiotics can linger in the system for days after the last dose.