Hi, Patrick:
I saw your query a while back, but didn't reply since I didn't feel qualified to answer. I see no one else has written, though so I'll give it a shot. You don't say what kind of orchid you have. I'll assume its a moth orchid -a phalaenopsis, since thats by far the most common one sold. If the tag giving the plants name starts with Phal. or maybe Dpts. thats what you have.
I have been growing and blooming orchids on my windowsills without a greenhouse for many years now, but I still have trouble getting some phalenopsis to bloom. They are considered the best beginner's orchid, and they are easy to grow, but they only bloom once a year, usually in the Spring, even though they stay in bloom for a very long time. I think one reason I have trouble with them is I pick up cheap out of bloom ones that have sat neglected in the "box store" for several months. Orchids are slow motion plants. They are very slow to die even with neglect, but also VERY slow to recover after they have been abused. Your plant may bloom next spring, after it has recovered.
The amount of light its getting is the most important thing. It is best in a sunny East-facing window. I grow mine in front of South-facing French doors, and they really get too much light, even though I keep them away from the glass and behind other plants that like the strong light. I move some orchids outside for the summer, but not my moth orchids. If you have grown and bloomed African violets, phalaeopsis like about the same amount of light and the same feeding and watering regime. They are supposed to like a drop in temperature at night. I turn the thermostat down at night all winter long. For more information, go to the American Orchid Society web site- www.aos.org I hope this helps. laelialee