I need advice

I'm 17 and just have convinced myself I'm pregnant (I don't actually know because I haven't taken a test yet but my period is late by a lot). My parents strict and the only sex talk me and my mom had was basically telling me not to get pregnant. I know that if I'm pregnant my family (not just my parents) will never forgive me. I need to buy a pregnancy test but I'm scared people will look at me like I'm to young. My cousin is 19 and I want to ask her to come with me or buy it for me but I'm scared she'll say no or tell on me... Idk what to do.