condoms

Okay so condoms are my only choice of birth control considering I have sex without my parents knowing since they don't want me to date which is crazy because my sister got to date at my age but thats a whole other story. I get paranoid quite easily every time I have sex but it has gotten better UNTIL I seen too many damn people getting pregnant like pregnancy actually in the damn air. SOOOO My question is: How much should condoms actually be trusted?