Private smell

I feel like I constantly have a nasty smell to my vagina. The only time I don't is for a few hours after I shower. But when it's there I notice it, any time I pull down my pants, open my legs while sitting, go to the bathroom etc. It doesn't seem healthy to me with the smell. For background I am 20, I'm sexually active, on the pill for 7 years, my boyfriend and I always use a condom, though we are eachothers firsts and std free (although not tested but considering we were eachothers first everything we're both pretty confident were std free), been together a year and a half, I do not exercise, and I don't eat healthy.