I would suggest you check out the Ortho book on how to grow orchids. You can find it almost anywhere. It's not expensive and has a lot of good information in it.

Some phals bloom during the warm months, so don't give up on your plants. If they don't set spike and bloom during the spring or summer, give them a bit more light (just a bit) and let them cool down by 15 degrees every day for a couple of weeks in the fall.

You say you have a sheer on your window. What part of the country do you live in? Anywhere north of the Mason Dixon line does not need a sheer curtain during the dull winter months. That only applies to the southern or western part of the country. Plants in the north need all the light they can get.