There are several factors that might be preventing your orchid from blooming. The foremost reason is light. Most orchid generally needs about 2-3 hours of light at the least to bloom. Moving your plants to a brighter spot can solve the problem. Another issue is temperature as some orchids require temperatures to drop considerably for them to bloom while some others require a day-night differential of about 5-10 degrees Celsius to bloom. High Nitrogen fertilizer will also prevent your plant from blooming and this is proven by lush growth and healthy looking plants that fail to bloom. This can be set right by shifting to a high Potassium fertilizer with an added Magnesium supplement. Another reason could be that you got yourself a seedling and it isn't mature enough to bloom.