How do I know if my vagina actually stinks?

FYI my underwear never smells. But my LDR boyfriend (whom I haven't met yet) said today "I really hope you're not one of those girls that have a fishy vagina." Then that got me self conscious and now im wondering how do I know if I stink down there and what level of smell is considered normal? I've never had anyone eat me out btw that's why I'm a bit worried.