Is it possible for a girl to reach 18 years without growing breast?

Yes, possible, but: She needs a medical workup to see what is the problem because while it's possible, it's indicative of abnormal development.

Define "growing": There is quite a bit of variation in the eventual breast size of normal women.Some will end up with oversized breast that produce back pain & other health problems. Others may end up with little or a "raisin on a pancake" appearance. If she has gone through puberty & started menses, she would likely just have little. If she has not had nipple enlargement by 13 and menses by 15 there's a problem