Hi im taking rifampin for almost 3months and I need to take OC because I had unprotected sex. Which pills will work?

Stop unprotected sex. That means stopping "unprotected" activities, by using other protection. One can consider an IUD or condoms. That can also mean stopping "sex", which can be simply done for 3 months (3 months is a short time). Birth control pills are less reliable (hard to say how much less) while a person takes rifampin, which may decrease the effectiveness of hormonal birth control such as pills, patch, or ring.