Wondering

Me & my boyfriend of a yr have been very sexual & have never used protection well we've had one lil pregnancy scare but I was just stressed. Now I don't want to get pregnant at the moment, me having 3 kids..... 7, 5 & 3 but I don't like most birth control since it really messes with my body. I've been using the calender to know when it's safe but still worries me. Is their anything else I can do to help prevent it. & no we don't use condoms mainly my choice I'm not a fan