The look and fit of a piece of jewelry often varies a great deal from person to person as well as between precise location of the piercing on the body. Unfortunately, a hoop nose ring that protrudes out from the nose more than desired (rather than fitting flush or snugly against the nostril) may be caused by the location of the piercing on the nose or even simply the shape of the nose. Hoops in high nostril piercings won't typically lay as flat as ones located a little lower.
The reason for this is because ones that are pierced lower and through the nostril curve will rest over the curvier, more rounded part of your nostril therefore fitting the curve of a hoop more snugly. Hoops will also fit more snugly on a nose with more rounded nostrils. This doesn't mean there is no hope, however, for those with a somewhat high nostril piercing or a straighter nose who want a flat, hoop-style piercing that fits closely! Of the more conventional solutions, a small hoop is the easiest way to get a close fit. As this does not provide a close enough fit for everyone though, I'd recommend searching for an oval-shaped hoop, rather than a round one, or even having one custom made (as they are still somewhat rare). This will cause the sides of the jewelry to lay more flat against the nose since the jewelry won't be quite as rounded as a normal hoop.
If you can't find an oval hoop or a place to have one made, consider getting creative with your jewelry and improvising with something other than a conventional nose ring. Just be sure to check that whatever you decide to use is made of safe, non-toxic material (usually metal or plastic that is safe for the body), that it is clean and sterile, that you are not allergic to it, that it won't deteriorate, that it will stay in the piercing comfortably but still be easy to remove, and that it is the right gauge size. Best of luck in your search for the perfect piece!!