Orchids are generally agonizingly slow growers, especially if they've suffered a setback. Don't despair, the fact that it's growing roots is encouraging.
Have you fertilized it with anything? They like a consistent feed of very dilute soluble fert, preferably sprayed on the leaves as well as enough to get into the medium to reach the roots. Remember they're epiphytes, so they feed through their leaves as much, if not more than through the roots. The roots function to attach to wherever they're growing in many species. In nature, the leaves collect nutrients that fall on the plant from trees, and the rain.
Try keeping a spray bottle with 1/4 strength soluble orchid fert in it, and spritz the plant a couple of times a week to encourage growth, and keep it more humid around it, as well. If indoors, and your windows are tinted like mine are, it's also possible it's not getting enough light to bloom. Move it gradually closer to a window or under a skylight, east facing would be ideal. No direct sun unless it's winter, more gentle.
