withdrawal bleed if pregnant

would you have a withdrawal bleed on the pill if you’re pregnant? me and my bf have sex with condoms but we did it without condoms once and I keep overthinking. I started my withdrawal bleed the next morning after the night we had sex without a condom. I take my pills perfectly. does that mean i’m not pregnant and don’t have to worry about it? it’d be nice if someone could explain it cuz idk if I can take my withdrawal bleed as a sign i’m not pregnant like a period.