sex on birth control

When's the best time to have sex when on birth control? I'm on sprintec and I don't trust it lol I need to know soon: my boyfriend is in the military and is coming home soon. We have had sex but I always yell at him to pull out (obviously) I don't want a kid lol and he wears a condom. I know this is like super personal but I have so much questions. I am also a super paranoid person so every time we have sex I think I'm pregnant 😂😂😂