Certified GKH Gardening Expert
You are certainly patient with that cactus! Is it an indoor or outdoor variety? They need full sun, well draining soil and low water. During the winter, once a month or less watering is adequate. The cooler and drier winter oftentimes prompts a cactus to bloom in spring.
Non-blooming cacti is usually due to lack of light or overwatering. Try fertilizing once a month with a non-nitrogen fertilizer like a 0-10-10.