Discharge a sign of pregnancy?

Hi! I’ve been having some white, somewhat smelly (SORRY!) discharge for a little while and my period is 13 days late. I’m taking progestin only birth control and i’ve never missed a pill, and my boyfriend wears condoms for the majority of the duration of sex (he never finishes without the condom on). I’m stressed to the max about this and I reallyyyy don’t want to be pregnant!!! I’m too embarrassed to go buy a pregnancy test considering i’m only 17, so taking one is my last resort. Is the discharge and missed period a sure sign of pregnancy? I’m having no other symptoms and it’s not unusual for me to have discharge like that but I just can’t help but freak out.